Yea, they deal they cut on the antimode products is pretty good. The antimode's do a pretty good job at equalization as well.
Omnimic should be fine, I think. I believe I read over at PETT that some guys were using it with 10 without issue. You may need to run a compatibility check and run as an admin though.
XTZ is compatible with Dirac Live, but that is an additional cost.
Omnimic can, I believe be used with miniDSP to generate custom biquads that can be uploaded. However, it's just doing the same thing as REW and the Umik, except you're paying $200 more than you have to. IMO.
Using Omnimic with miniDSP is similar enough to using REW with a Umik, IMO, that it's not worth $200 more than just purchasing the Umik and spending a little time getting everything set up. A USB mic is extremely easy to set up more often than not and there is plenty of user support for REW, along with a big manual. YMMV, but I think if you're taking the time to spend all this money, go through the time and trouble to set up the sub with proper placement, take measurements, and do some custom equilazation that saving a couple minutes (or maybe no minutes) and spending an extra $200 is a waste, especially if you plan on learning REW anyways.