Hey, i went from a rt100 to a kx80 with no prob. But there is a world of diffrece between the two, trust me, if you arnt going to race dont get a raceing bike!! its a wast of monny and time, i trail ride my 80 but i had to regear the srockets so it coulde hill climb and all of that, and you have to change the oil every 7 hrs, clean the air filter after a full day of rideing, and replace the slincer packing after 2-3 days of rideing, and if you dont do all of that you will start fouling plugs out and i have foulded them out when i was close to 7-8 miles from camp. and the top end depending on how you ride it will go out once a year, im not trying to talk you out of it or anything, but just warning you befor you go blow all your monny on a bike that will be nothing but proboms, but im geting ready to sell and and by a xr 200, but i would test ride a 80 to, but they are alot of fun when they run right,
well good luck and let us know what you do!
Philip
p.s, there is such little diffrences between the diffrent brands it really doesnt mater, i bought a kx becuse i like green, lol