I've been involved in some online discussion. Comparing the UMC-1 to the Model 998 is apples-to-oranges in several regards. The XMC-1 would be closer when it is released eventually, but still not necessarily a direct equal.

Availability: The Model 998 isn't here yet. The UMC-1 is - at least I think they're selling them right now (they halted shipments a couple times as they are still working out a number of bugs).

Features: The Model 998 will offer what looks likely to be better video processing than the UMC-1. It will offer Trinnov room correction, while many seem to feel that the UMC-1's Emo-Q is not worth using and the auto setup itself is still buggy. The UMC-1's bass management implementation is decidedly odd.

If you are looking closely at the UMC-1, I would suggest looking at the AVS thread for details on the unit's current status. Here's a link.