I havent ever dealt with him on selds, BUT have dealt with him a fair amount in person about racecars. Top notch guy from what I know of him. I wouldnt hesitate to take his word on what he says or have a problem buying anything from him.
As with buying anything used, look it over good and ask plenty of questions.
I bought a pair of sleds and a trailer from arnie about 6 years ago. You are right, they are rentals from out west but I never had a problem with the ones I bought. The better sleds are sold first with fewer miles on them so if you decide to buy from arnie, sooner is better. He is a pretty good guy and I would do business with him again.