Worth it for sure IMHO. I have a regular MM that's about 3 months old, and I had (just sold it to a guy at work) a Q3 one, and the light from the Q3 is much whiter in comparison to the other one. Not to say the other one is bad, just kind of a "warmer" white with a slight greenishtint to it, but it's still way whiter than an incandescent.
I just bought a new MM+ and BB 500 and bought the Q3 emitters separate so that I would get the two LS's I pulled off of the boards for only $10. Plus, I'll have a BB 500 with Q3L /ubbthreads/images/graemlins/cool.gif, and I don't think anyone else has done this yet (probably, but I haven't seen anything about it)! /ubbthreads/images/graemlins/grin.gif