After a year and 3 months of 450F'ing, I sold my '04 on Saturday. Amazingly- and I know this is going to sound crazy- it was the '05 KX125 that killed it. I've been battling elbow tendinitis since July and finally got to ride the KX (I bought it in late July) on the track last week. When I did, I had a blast and came to the conclusion that I'm all about corners. What I like to do is to simply make a good corner. I really don't care about lap times, don't care about top speed, don't care all that much about jumping (although jumps are fun)- what I like to do is corner. I like to rail berms, slide the inside line, change lines mid-turn, and so on. The KX is superb at that sort of thing and the '04 YZ is not. So, Big Blue got sold on Saturday ($3500, in case you're wondering- I sold it to a friend and was not trying for top dollar) and I'm back to premix and changing pistons/rings every 25 hours. I'm glad I rode the 450F for awhile. It was THE most confidence-inspiring jumper I've owned, the straight-line stability was GREAT, the bike was dead-reliable (up to 35 hrs, anyway) and the thing never lacked for power. After riding it for awhile and then going back to the 125, I'm a better 125 rider. The 450F _forced_ me grip with my legs and knees, not grip the bars, and pay more attention to body position. Plus, I got used to riding at a higher speed. If were racing and cared about my results, 450F would definitely be the way to go. But I'm not and I don't, and for me it's all about fun. I honestly think I could be happy on a KX100 (and at 5' 5" and 160 lbs, I could just about ride one! ) Anyway, adios and thanks much for the advice and conversation I got here. I'm off to live on the 2-stroke forums. P.S. If you have an '04, get a Dr. D flywheel on it! That was the single best modification I made to the bike.