Hi i had a 2001 yz 80, i bought a 2005 ktm 125 after and since i got the 125 i have enjoyed every second on it, it is a very reliable bike and is easy to strip down etc eg get at the airboot unlike the yz,and cleaning the airfilter etc after every ride, i had a go on yz 125 and i thought it was alot harder to ride after having a go on ktm sx 125, the yz 125s clutch ,is alot stiffer and the brakes are quite slow while the ktm is a nice smooth ride with racing suspension,brakes,v force reeds,excel rims as standard unlike the rest of the 125s. when ou are the correct height for a 125 i would highly suggest you get a ktm 125 the power dileverence is alot better and the gearbox is excellent! i love my ktm 125 its light nimble and has playfull handling it is an excellent bike!