I have on '04 WR 450 and '05 450 EXC. Between my 2 bikes, the WR has a harder hit on bottom end and better brakes, but that's were the WR's advantages end. Actually I think the harder hit on bottom end is a disadvantage in most cases (for me) as it makes it a bit harder to handle in situations were traction is scarce. The EXC produces as much power, but much more smoothly. When riding, the EXC feels much lighter (not when lifting or pushing the bikes though). I think this is due to a lower center of gravity. In any situation, I am faster on the EXC, and it is less tiring to ride. Suspension on the EXC is awesome. The EXC seems to have better components for the most part (hydralic clutch, bolts made from better steel, etc.). I suppose if you were just going to cruise around on fire roads the bikes might seem close to equal.