I'm about to spend some money on this. I think I'm at the point now the Fireface 800 is starting to be the limiting factor for me - and I am starting to get enough outboard recording that it would make a great compact hub for that application so I could move it to B, but one forgets the luxury of the FF - I get permanent use out of 26 ins for a great price. The other reason I want to do this is to be able to move to analogue summing, which i know you'll approve of, but I think 16 channels may not quite be enough, so I'm looking at some kind of 8+16 solution - but its gonna be pricy.
I've also been looking at the Aurora 16, the Crane Song Spider, and am starting to read a little about Apogee Symphony. I totally agree with you, there doesn't seem to be quite as much on the market as you would think and it feels like something new may come along.
I'm going to take my time on this one; I'm contemplating selling my Massive Passive although I dearly love it and going for the Spider, running ADAT into an Apogee Ensemble and then Firewire onto my G5. My alternative is a very big desk running into the Aurora 16 but I'm not then sure how I would process the ADAT. I'd have the Fireface for additional routing but the more I look at it, the more I feel like the Fireface represents such an excellent setup for me, I'm quite unsure where to go from there.