I have operated, both machines. The 7720 was the very first of the T2 machines (it still even had the yellow cab but the rest of the specs were t2) and I now have a '96 spec 9500 (data center, bearing on walkers, extra lights, air seat, ect.) And you wouldn't get me back into the 7720 for all the tea in china. I've now put over 1000hrs on the 9500 over 3 winter and summer harvest and (touch wood) no major problems to date. You don't have a motor roaring in your right ear. The airconditioning is miles ahead, cab controls ect.. I could go on and on about the operating enviroment, simplicity of servicing, capacity equivilant to an 8820 or better. ( I had our machine with a 30ft head cutting at 12km_hr in 20 bushell wheat with no loss) For that bit extra money, you'll be a long way ahead in reliability and confort. But as with any second hand machinery, be have selective about what you buy. Particulary with more modern machinery. If it looks like it's spent all it's life in the weather and never seen a grease gun, of course you can expect troubles with the electrics.