I used them both for several weeks (first LeeDroid, then this one) and they behave similar. You can't really feel major difference in speed...
What I do notice is that the rotation reaction is slight faster on LeeDroids ROM (certainly on the lockscreen), but battery life seems a little bit better on this one (which is weird, since they both use the same kernel).
Just for the record, I have over 150 games installed and about 80 other programs, and it just keeps going without hesitation. So this ROM is fast enough, no matter what you'll be doing on it!
Overall conclusion: go for the looks ;) This looks so much better than Sense