Great photos and write-up and timed perfectly as I am just now fitting my Silvio S-30 and working to get a slightly more upright position. It appears the Volae comfort seat is longer in the upper back than the carbon seat that comes with the S-30--is that correct? That appears to eliminate the need for the headrest, correct (for which you reversed the headrest rails)? Thanks for your sharing!
It depends-- the Comfort Carbon XL (which, being a tad taller than my dad, is what I use on mine) is long enough that you can use the standard CruzBike headrest, should you choose.
The Comfort Carbon L rises a bit before second scissor-clamp hole.
It is probably more true to say that the CruzBike seat is straight/flat, and these seats are curved and, when they fit, provide more support-- In fact, if I didn't end up with a pool of sweat without the ventisit, I'd find that the Comfort Carbon seat is pretty dang comfy without the ventisit (but, since swamp-bottom and swamp-back are unpleasant... the ventisit is imperative!).
I suspect he will end up adding an ADEM-2c headrest, but that was a week away when I took the photos.
You can see the Comfort Carbon XL on a Silvio S30 in my tilting-trike-prototype build
thread.
Incidentally, the new S30 frame is a step up, in my opinion. The fit and finish are better, the frame has been tweaked in subtle ways, and I just heartily approve. You're in for a treat!