I have a buddy who loves kdx's and he has owned at rmx for about 5 years now. The bike is pratically stock. The speed is very comparable between the two and the kdx has more aftermarket parts. The one item over the kdx that the rmx possess is the front fork. The kdx to him was much more fun do to the engine characteristics. If your really ready to heave your old kdx then look at bikes such as KTM, GAS GAS, and TM. The make high quality two-stroke enduro machines. The disadvantage over these is they cost quite a bit more than a KDX. Since the fork is the main problem with the kdx you could just transfer a entire front end from another kawasaki. I put a 96 kx250 front end on my 96 kdx and it makes all the difference in the bike. The steering stem is used on that front end and easily adapted. So like u thought, go kdx, because it is so much fun to blast by mx bikes on a kdx.