I'm using a Yamaha O3D mixer (big brother of the O1V) so it goes without saying that I highly recommend the O1V. It's the best mixer around at the price and the effects and dynamics processing (not to mention the scene memories etc) are something that you can't live without after you've used them!

Regarding cards with ADAT connectors- check to make sure which cards already have Mac drivers or not. Sadly, many manufacturers seems to be bringing out PC drivers 1st and then Mac drivers much later (which really is strange to me!!!!). If you only need a single ADAT I/0 port, check out the Korg 1212 (which is now getting a bit old but is still very popular), Sonorus StudI/O (2 adat I/O with 1 port configurable to SP/DIF I/O). Steinberg have just brought out an audio card with ADAT I/O which should work just fine with Cubase (check whether the Mac drivers are available!). Motu have the super huge 2408 and 2408 mark 2 with 3 pairs of ADAI I/0 (mabey a bit of an overkill for your set up but you never know what may happen in the future!!!!). Creamware's Pulsar (with it's own DSP for it's mixer, effects, synthes etc). The new Echo cards (Gina24, Layla24 and Mona24 each have a pair of ADAT I/O's as well as analogue I/O). These are just a few of many more on the market now available.

My advice is to check 120% that you wont have any compatibility problems between the software and the card!

Hope the above helps.