As I've kind of always alluded to an Ultimate Synth of sorts, which is to some extent subjective, and because I genuinely would like to hear about how I could improve it, where I might be wrong, etc. I thought I'd post my concept here. So this is the current state:

So why am I calling this the ultimate synth?
Like probably many of you, the idea of being surrounded by various synth makes and models is something I think is awesome. However, the thinker in me has always longed for the perfect interface and unlimited sound sculpting options. Today many people accomplish this by just using an assortment of synths, either physical or software in nature. While great in so many ways, it is also frustrating. Each synth has a different interface, different limitations, and different strengths. I think although the options presented by such an approach are plentiful, they are not truly unlimited. (either at sound sculpting or with regard to the modulation options.)
So if you want to have it all with the least amount of limitations (outside of interface limitations), a DAW with a slew of plugins, and a beefy system is arguably the most powerful and limitless solution. However, even in software there are always limitations, and not every plugin works intuitively with the whole system or at all. There is also the issue of workflow and interface. Having all the options in the world and no way to really harness doesn’t really do much for you. This is one of the primary draws for me about modular synthesis. I can route signals from where ever to whatever. I can do things that many software plug-ins have never thought about.
Enter the physical hardware synth. A lot of them are analog, and all of them boast of how their physical controls make it possible to focus on using the device instead of learning it. Still they are usually constricted by their physical limitations despite the best efforts to create them to be used in as many ways as possible.
I label a synth as the ultimate synth, if it presents to me the most options for sound design and ways to control and use that sound. I also call it a synth, singular in nature, because I feel like having one instrument allows you to focus on it, and can therefore master it much better than trying to remember a billion different settings and knobs across a host of synths in your studio. This is why I moved into the modular synth world to begin with. On a modular system you can route things in ways that software plugins, in some cases, have never even thought about. You also are dealing with one system, that is comprised of many different parts, but that operate as a whole.
A purely analog modular system is powerful, but expensive, and to really be near limitless, very large, and not in anyway easy or intuitive to use. (This is not a problem for me. Options means depth, and that usually translates into complexity.) Just think about the time it takes to patch up a 9-12U. Now imagine a whole wall. Seems like heaven, and it is, but this time takes away from creativity and can also make one afraid to take chances. Do you really want to mess with the patch? It is perfect now, are you sure you want to reroute this or change this?
Digital modules however allow the modular world to do things in a space that isn’t always possible in a fully analog implementation. All digital modules are employing DSP. All of them play by the same rules in terms of what is going on behind the scenes. And lest we forget, digital modules allow you to do things also not possible in the analog realm.
This is why the SSP is the nexus of my setup. It can do anything that can be done in DSP, and because of the horsepower under the hood it can do it in multiples across many different types of DSP simultaneously. I have analog oscillators, filters, modulation sources, and VCAs. The SSP helps to take advantage of all of it, and give me an infinite range of things I can do with them. The SSP gives my whole rack wings.
I can also sample in any of my modules and multiply them in the system through the SSP. As I swap out oscillators and filters, looking for the ones I really like, I will be able to keep it all through the samples I’ve taken. This means that as my system changes but stays the same size (maybe) my rack just continues to grow with every sample and patch saved. I can do this on the 301 as well, but as it's sample resolution is lower, I tend to use it for VCA, filtering, and some effects on background sounds, etc.
This functionality is an important part of the instrument. However being able to control it in the most comprehensive and tactile manner was an important element for me as well. Where some see the modules controls as the solution to this, I've never found a module that I felt I could play in the same way I could a piano, etc. Some of the things I’ve been able to coax out of my analog modules sound great already. But being able to control them as I would an acoustic instrument lets this synthetic sound (in some cases) breathe with life and feeling.
In my rack, the FH-2 allow me to plug in a host of controllers (Roli, Haken, Linnstrument, sequencers, DAWs) as a means to control modules and can really help me just build up massive sounds and soundscapes and take advantage of that range of control.
Of course these controllers can be plugged into the SSP directly via its USB host ports. I can use the SSP as a midi to cv converter. This means that the SSP can host these controllers and supports MPE functionality directly and out of the box without needing the FH-2! What I’ve done in these cases is plugged in a roli and used most of the parameters internally, but have routed the release or Y axis to an an output on the SSP to be used on other modules in the system. Very powerful routing options, and just incredible to be able to put this control right where I need it. I personally prefer to use the high resolution/sample rate outputs of the SSP for audio output or modulation signals though, so that is why I also have the FH-2 module.
Because of this, Ladytron, my eurorack setup, is my ultimate synth. There isn’t anything I can’t do with it, and even more so that I wont be able to do with it eventually as more and more modules are developed for the SSP.
One thing I think I should probably mention again is that the SSP is the main hub of this ‘vision’. The reason for this even though I have a ER-301 is that the SSP just has the horsepower (about 10 times the horse power of the 301) to help the system as a whole to shine.
With 16 DC coupled inputs (rather than AC coupled) I can use the inputs for audio, CV, and gates. The recorder on the SSP can sample all 16 inputs (regardless of the type of signal) as well as all of the 8 outputs (also DC coupled and able to output CV,audio, or triggers) and all internal signals. With the SDK it possible to extend the SSP continually. Right now I think I'm only one of a few actually working to develop modules. I would love it if more picked it up, because I think the cost value ratio on the SSP is through the roof and any development on it just increases that.
The upgrade-able nature means that as features mount, processing power can always march right along even though it is already super powerful. Direct control over MIDI through the USB connections to include MPE means that I don’t have to use my inputs for control if I don’t want to. This flexibility just means the SSP is poised to do whatever I need. Whether that is some super massive front line role, or some low key background helper. This whole ultimate synth would not be possible without the SSP.
Thoughts? Do you have any suggestions? Please remember this is just the logic I use. I'm not trying to say some other way is wrong. While I've created what I think is the lushest field for me to explore, I am still completely at the beginning of discovering all that the nearly infinite field contains.

This is a more current past iteration:

Details can be found through out the thread here. I will add, that getting the system to be as small as possible has always been a design goal.
and another more current past iteration: This is the current state of the synth: