I would think that if you can hit 300 or more, than it will be very similar in performance to tight timings at 265-270. You could get lucky with some TwinMOS SP or similar, but unless you go ahead and spend the bucks for either the OCZ PC4000 VX or maybe the new Mushkin Reds, you are going to be gambling. I've bought 8 512 MB sticks of UTT and either because of lack of skill, bad luck or bad mobo, I can't break 250 with any of them in dual channel. I've had fun trying, but that's all.
I think that with good TCCD sticks already in hand there really is no need to chase UTT unless you just really want to, 'cause you certainly don't need to.
I think part of the allure of the UTT for me has been that extreme voltage thing...fire that Booster up and see what those puppies will do. It is probably not the best solution, long-term that is, for the rest of the system, though.
I hope I don't burn the house down one of these nights!