6500 2s gets my Tekno thru 10 minutes on large 1/8 tracks, I usually only do 1 or 2 warm up laps. My 7200 I can easily get 12-15.
I have noticed almost all of the 7200's cases cracked right where wires come out of pack, even after 1 or 2 runs, I have about 8 of them and 3 6500's. If you use the bullet packs this wouldn't be an issue but I like my deans. Also because case is same size as 6500 the cells with make the pack swell a little compared to the 6500's. No issue with that as long as case doesn't crack on sides.