A couple of things for you to consider.
I have a Yamaha DM1000 and have installed 2 MY16AT expansion cards. This gives me 32 channels of ADAT output (and, indeed another 32 channels of input) which I interface into my computer via an M Audio Profire Lightbridge which outputs Firewire. I've been using this system for going on 3 years and it's been flawless. With my mixer, to get beyond 16 mic inputs you need to add external mic preamps for which I also use the MY16AT cards, juggling the inputs and outputs as required.
However, I'm thinking that Firewire is a system on its way out (look how few computers now have Firewire or and Expressbus slot to install an adaptor in) so, I suspect my next change might be to replace the ADAT with a couple of MY-16-AUD cards which would give me an Audinate interface running direct into the computer via ethernet. Up to 16 in/out you can connect directly to a computer, beyound that you use a gigabit switch for up to 48 channels of in/out.
At least with pro gear (and at 32 channels you're getting into that range) you're going to find that the world is moving to various ethernet solutions rather than Firewire (and USB isn't really recommended for that sort of track count).
