Well guys, my dad has an 03 red and black Ds650 and i got the 450r r, and personally, everytime we race down the road, he barely passes me on top end, but he still walks away, well more like creep, but yea, i was impressed with the 450, both machines are bone stock, well not mine any more i changed the bars and shaved my fenders, and soon i plan on gettin a set of itps, propeg nerfs race cam, etc, i will post that stuff up later. How ever, the bike you prefer will be depending alot on the rider and the type of riding you do, i havnt been to any dunes yet, but my dad had his ds there and he loved it, i have yet to take out the 450 there and as well try the ds there as well, However if its trails or mx, me self personaly id take my 450 over the tank(ds) for my self i find it toooo heavy for tight trails or mx track, the bike it best on wide open trails, and even yet i still like my 450. This winter will be fun however, we run alot of rivers down here, that are awesome with studs, and u fly( sleds can have a hard time to keep up down the river surprisingly) and well when winters comes well see whos king, by then tho, my bike should leave it, i wanna add sum stuff to the engine and add the 15t sprcket and 22 ince tires for the extra top end on the rivers and lake, thats wat ill use most in that time, but yea, as for wich is better to me the 450, my dad likes his 650 a bit better tho, but he is a bigger guy and it is a bigger bike.