He's one of the few US based sellers of geared motors on ebay, and has them far cheaper than anything I could put together myself buying the parts ala carte. Thing is, he's often out of stock on geared kits. I've bought two 500W rear geared kits from him, both in 2015. These were 36V with 810 LED controller. Very simple. Only a sample of two, but both have worked fine for me. The geared 500W motors are not speed kits though. You should get close to 20mph on a 26" wheel and 36V, but these are intended for easy assist at bicycle speeds.
Double wall rim and thick spokes make the wheels. Typical product out of a chinese shop. Keep a spoke wrench handy, learn how to use it, and all should be fine.
I cannot speak to customer service. I never had an issue, but I had some newbie questions in 2015 (What battery should I get? Can I run on 48V too?) that were submitted via ebay that were ignored.
I believe that Dongdianebikekits.com makes the motors. My assembly manual was printed by them anyway. Their tech support email ignored me too.