You may have seen what you said, I'm not knocking you for that, but my piped R destroys my piped 416ex all day long.
One thing to take into consideration is that it will take a few hours on the R to learn how to launch it right. When the yfz came out, I was beating every stock yfz that pulled up to the line on a standard bore, piped 400ex because they didn't wind the motor up high enough on the takeoff. This took place on a 300ft track, and yes they were gaining on me at the end. Except for my friend that has a yfz, because he knew to rev it like a 2 stroke on the take off and beat me every time.
If you only race in a straight line that's cool, but if you ride the mx track or in the woods, you might want to see how moch better the R's suspension is than the 400ex also. From my experence the 450r is a lot better.
04 trx450r pulse charger, boones head work, 480cc 14:1 comp je kamikaze piston, ac nerfs and stadium bumper, hrc kit, pro armor chassis skid, powermadd handguards, fcr 40mm carb, prodesign case saver and killswitch, tag t2 450r bend bars, denton steering dampner, works clutch lever/ hot start, k+k graphics.