ST Audio was not so recently acquired by ESI...which is a pretty good company. Underrated, generally quality driver, and a fine driver architecture. The ST Audio stuff are generally older designs, though, made to work with the older drivers. Combination of age and obscurity would keep me away.
I actually like the E-mu stuff, but the drivers are admittedly limited. I have and 1820 and I use the ADAT on it all the time. The limited drivers (no multichannel WDM, so useless for your ADAT in if you want to use a WDM application, no GSIF, no multicard) are a valid concern if you see yourself needing these now or in the future.
If you've got the money for an 800R, I'm guessing you've got the money for a nice interface to go with it, and there aren't many that are nicer than the RME line. The Digiface gives you 3x ADAT and a headphone/line out to monitor. The Multiface gives you just 1 ADAT IO, but a whole slew of analog ins and outs as well.
If you insist on going cheaper, there's the recent stuff from Echo and E-mu. Plenty of people on boths sides get good work out of them. Echo has a pretty good reputation for good product and drivers. While the E-mu may have the better converters, since you're using ADAT, remember that you're not going to be using them anyways as the AD conversion is happening in your preamp anyways.
If you're lucky, maybe you can find a used EWS Terratec 88D. Heard nothing but good things out of this card's users, but you'll have a hell of a time finding it anywhere else but the second-hand market. Oh, and it's cheap...around the 100 mark or less at the ebays and flea markets of the world. It also helps that this thing will multicard with other EWS cards for expansion...
