If you know your going to be grabbing a board feed with the V3, you could switch the internal attenuator jumpers to professional which buys you about 20db of attenuation...that would help alleviate a hot signal from the sbd. Otherwise I have yet to plug into a board where the soundguy couldn't lower the levels at the board, I'm sure there are some boards that don't have that option, but most of the time they should be able to help you out.
I've never used just the mt for a patch, but have used my D8 dat recorder a few times...and I've preferred the V3 or even my w+ ua5 in front. That said, board feeds can be such a crapshoot as to what is in the mix and how much, that which A/D you use is the usually the least significant part in the overall sound.
Before buying just an external A/D, I would think about something like a HD-P2 (or Edirol R44 when it comes out)for the board feed that you could send a wordclock from the V3, that way you could still run your mics>V3>MTII (or R44), plus sbd>HD-P2(or R44) and you would have the option of an easy matrix in post.
1/4>XLR & RCA>XLR's are a good thing to have though, you'll have most of your bases covered...the most common you'll run into are XLR or RCA outs from a board.