I have been reading about over-volting and finally tried it and it has been great. Started with an old chain-drive Schwinn S750 (24v 750w) that I bought off the classifieds. Someone had rebuilt it as a 24v scooter, although I think some did come that way. It went, but not much zip. Then I bought an old Schwinn S1000 off the classifieds. It is essentially an eZip 1000 with the direct drive. I drove that and liked the pick-up of the 36v direct drive, quiet too. Could finally climb some of the hills near my house. I was looking at both scooters and noticed they were essentially the same except the motor, so... I took the 36v battery, throttle and controller from the S1000 and put them in my old S750. Wow, what a difference. This thing really goes compared to my other scooter, a stock 24v eZip 750. Good acceleration, seems faster than the direct drive S1000 both in pick-up and top end, and it goes about 6 miles on the SLA battery pack. Can handle the same hills as the eZip 1000 direct drive motor. Nothing seems too hot or weird. The chain drive is nice because it coasts easier than the direct drive, but it is a little noisier. I have put about 20 miles on the scooter and everything seems good. The motor has a bit of a higher pitched whine to it now, not bad, actually sounds kind of cool. I ended up swapping the forks so now I have full suspension and front and rear disc brakes. The 3 batteries fit on the compartment that was originally built for 3 batteries. The whole project turned out great, a fun ride.
Thought I would post because I have gotten so much help from reading other people's experiences on here. I love this set-up I have now. Out of all the scooters eZip 750, Schwinn 750 and Schwinn S1000 (eZip 1000) this combination ride has been the best.