I got the jetting cleaned up and it has made me question the need to drop a tooth on the front sprocket. Even so, the very bottom end still does not compare to the grunt of the WR-450. However, it will pull the front end up very easily once you get the RPMs up a little. The powerband has three "levels" and is very manageable, even without a flywheel weight, but it is VERY easy to kill the engine with the rear brake. It doesn't bog if you try to roll the throttle on in too high of a gear, it just feels flat. I'm very happy with the transmission spacing and spread and will probably try the flywheel weight; I just don't want it to tame the power delivery too much. It's hard to resist the temptation to ride it on the pipe all of the time; I may just have to stock up on rear tires.
After additional back-to-back rides between this bike and my WR-450, it is evident that the Race Tech Gold valves and revalving on the 450 are "plusher" over rocks, ruts, and washboard. Some of this might be attributed to the additional weight of the 450. The YZ has a more progressive feel on the big stuff and isn't bad over the little stuff, but isn't as plush. I will very likely revalve them at the end of the season, just because I'm spoiled, but it is definitely rideable in its stock configuration.
The lighter weight of the YZ is very apparent and it sure makes it easier to slow down and make corrections, both in the air and on the ground. It's an absolute hoot to go into the corners sideways due to entering a little too fast! It doesn't wear you out as much trying to move the bike around, but it requires more effort shifting and more judicious throttle control.
I'll have to modify my license plate mount; the back tire grabbed the plate at full travel and completely bent it up under the fender. I'm lucky that it didn't grab the mount, itself, and rip off the entire fender.
I originally had thoughts of selling my 450, but after 6 years of riding and tweaking it, I'm not ready to give it up. It's fun being able to pick a bike for each ride/trail and, no, there is no way I'm selling the YZ.