I have been running the u89 for a few months now and have had the chance to run in a variety of spaces including outdoors at ACL, inside at the 930 club(1K people), 8x10(400 people), Rams Head Tavern(small club 245 people).
What I can tell you is that the flexibility of the mic is very appealing to me. The ability to switch on the fly and run a bass roll off have been invaluable. Mostly though it is sound.... crisp, clear, and detailed. Some of the recordings I have made in the last few months are fantastic - the best work I have done and I credit the mics with holding up their end. When I looked for new mics I really wanted to stay away from things that colored the sound - either on the high or low end - and did a great deal of research before making my decision.
Some of my friends who are not tapers can pick the mics out of a blind test without fail and all remark on the quality of the soundstage and the clarity of the notes.
Does this make them better than the u87's - no, just better to me and what I wanted in a mic.
Before dropping mega bucks on either of these try to find sound samples of bands you like, in venues similar to what you record in and recorded with the same machine that you use... there is so much out there... then roll on - I am sure you would not be dissappointed with either decision.
CQBert