A 550 reed motor I bought I started and it ran, thought sweet, until I water tested it... It wouldn't go past half throttle... I was so bummed... It turned out to be the pulser coil, but the moral of the story is, you should test drive it, or have him test run it... Just get it out into the water because your not going to be garage riding it only are ya?
Had I tested that motor, I could have talked the guy down more...
If your worried about falling down, just stay on your knees and tell the guy you don't want to get wet...