To often people complain about bad service or a bad experience. I try to make it a point that if I get a good experience then I try to share it.
So, I recently decided to upgrade my 70-200 f4 IS to the f2.8IS II, but the used prices I was seeing around were still pretty high. I saw a listing for a used one from LensRentals for $1,800. I liked that they supplied high res pics of the actual lens and they provided test result. I thought I would take a risk. Turns out, it wasn't much of a risk at all.
The lens I ordered came as described, but the IS module went haywire. It must have been damaged in shipping. I called them, they had me try one thing with cleaning the contacts, and since that didn't fix it, they paid for the shipment back and sent me another lens (which actually tested even better than the one I originally bought).
I was always able to get a hold of someone and they were professional from the get go.
I would buy from them again and recommend them to others. If you don't mind a few beauty blemishes on the lenses, it is really a no-brainer.