Wow thanks I didn't know that stuff. I'm also with you on the absolutely bananas $800 price tag on that syn2 loading dock btw. And yep, the decision to make the input stage universal seems... ill advised and counter to the entire point of such a system.
It's kind of a shame there's no system that truly replicates all those preamps one-to-one. But like @ZEN Amps said, the poweramp is also hugely influential to the tone as well, and as long as there's no real comprehensive selection of tube poweramps out there, true modular analogs to the tones everybody wants can't really be achieved in this format, which is a shame. They can get close, but not 100%. Along that line of thinking, it's strange that no monoblock tube poweramps for guitar have ever really been made, huh. Seems like companies have always approached rack vs heads as two entirely different universes. You would think in the 80's, at least Marshall would have built something like a rack mountable JCM 800, if not separate JCM 800 preamp and monoblock JCM 800 power section as rack gear. Mesa made a bunch of rack stuff but their studio pre and quad weren't really the same preamps as what was in the heads, and the Triaxis (as much as I love mine) was also entirely different than the heads. They made rack poweramps but again, all stereo.
You know, I don't think it will ever happen, so much so that it's almost embarrassing to even type it out, but if somebody was to actually try to develop the modular tube preamp idea the right way and make true 1-to-1 representations of all those famous preamps, and then companies were to make a bunch of monoblock poweramps representative of every major tube type (KT88, 6L6, 6V6, EL34, EL84) that would each handle a quad of those tubes, and where each poweramp let you adjust basically every poweramp parameter that matters (full watts switchable down to as low as possible, pentode / triode, class ab / a switching, knobs for Presence and Depth and control over Presence and Depth frequencies, global Negative Feedback control, etc), then you could lay the groundwork for true, actual representations of pretty much whatever amp you wanted in rack form.
It'll never happen though.