Mark has great CS. Back in March I ordered a Cigar Caddy for a herf. After ordering, I noticed that it was listed as out of stock on the website. I sent Mark an e-mail asking about the status of the order. I had a reply back within 10 minutes that I had got the last one in stock, and received it in plenty of time for the herf.
A few months later, I was having some issues with my desktop RH. I called Mark to see if he had any suggestions about the Puck humidifier I had ordered from him, and got his VM. Mark called back about 2 minutes later, asked me a few questions, then said, "You know what? Let me just send you a replacement." No issues since.
I also really like the fact that he hand writes a thank you on his invoices.