Okay, I got my first ride in (about 35 miles) on the new WR450. I'll list my impressions along with some info. I left the suspension stock settings for now with no adjustments front or back. Only minor mods before I rode it, snorkle and baffle both out. Dealer cut the throttle stop without even asking (great service!) Runs a bit lean as expected but still ran well. JD kit to go in when it gets here. Just some background: I'm 175 pounds and about 6 feet tall. I have quite a few bikes to compare it since I've owned a variety in the past 4 years. Came off an XR400, WR426, WR250, and my latest which a buddy rode most of the day along with me is a 250X. First off, the '05 450 stock suspension I liked a lot better than my 426. I have a bad right knee that gets water in it if beat too much and it felt good after the 35 miles on the stock setup. The 426 stock setup made it hard for me to ride, even after I set it up softer. The 426 was a flat out monster but I had more mods on it than I've got on the 450. It was a bit harder to control but flat out hauled. The new 450 has lots of power but it seems more controlled to me. Works out well for my type of riding since I am intermediate and not an MXer. I swapped back and forth between the 250X and the WR450 and have to say I would be hard pressed to sell off either. The X is just a different ride. It's setup stock suspension but softened a little on compression and increased rebound damping. It handles slow technical stuff very well but feels a bit squirrely on the front end compared to the 450. That could be due to the stock Dunlop front tire on the X, suspension setup, or just that the 450 pulls the wheel up more. The X feels like it jumps around a lot but it stays on the trail. My buddy actually likes the X due to the softer seat (he doesn't stand up much). Comparison to the XR400 isn't much but what you'd expect. The XR is a tank. I got good power out of after an Edelbrock carb was installed so it pulled the front no problems. Just heavy to throw around. The 450 obviously is much lighter and thinner. The '05 450 has a smaller tank and feels more like a YZ with the seat going up on the tank about the same as the 250X. Seat height is lower and I think it matches the X (or feels like it). Weight seems to ride lower now than on the 426 so it handles well when you throw it around. I like the balance front to back on the suspension also. I had a hard time climbing some hills on my 426 but we did a couple runs on a steep hill with the 250X and the 450 and I actually could climb better with the 450. Probably the power difference made it easier but the 450 also hooked up without spinning out too much. Even on the first ride with the X I didn't climb as well. I wish Yamaha would change to different grips but that's not a big issue. The 450's frame makes it much easier to work on the carb but the AIS kind of gets in the way (but it will probably be gone soon). The Honda has a nice frame but the carb is a bear to get at. Overall, I really like what Yamaha did with the 450. The WR light works great as well. If you do the mods you need, it is a super bike. I like my 250X as well but it's nice to feel the power of a large engine sometimes. My buddy said the 450 scared him but he used to ride the 426 and loved it. I think it's just been a while since he rode.