The problem with the current range of cards is that DV is usually considered good enough for SD capture - you want uncompressed, which is something else (and until recently quite uncommon on the more affordable hardware, so the Intensity Pro is quite a bargain if it will do the job for you).

I don't see that the MXO2 will give any particular advantages in your case - it does pretty much the same thing for SD analogue sources (Matrox themselves did a comparison: http://www.matrox.com/video/en/products/mxo2_mini/intensity_pro/ which suggests that the benefits are entirely in the HD arena).

The company that I work for is a dealer for both, but SD processes only get the most cursory testing here (and only ever in PAL). Shame you're (presumably) not in the UK, or else we could have organised a try-out - it sounds like the work you're doing is considerably more interesting than most of our existing clients!