I got a climate control board from him, did the exchange service with the core charge. The repair guy took way longer than I thought was possible to certify the old one as repairable, but Mark put up with weekly emails from me asking what was going on. Always responded quickly, and reasonably, and shipped fast when I ordered the part.
Overall? Would order from him again, but possibly not if there was a core exchange involved. He comes off a lot more professional than some of the comments I have seen here imply.
Nick