I've purchased a lot of stuff from CMMG including two uppers, carry handles, LPKs, furniture...probably more but I can't recall without looking in my checkbook. Every transaction has been flawless, John and Jeff have always been very helpful and patient and their products are second to none! Plus, they don't charge you extra for using a CC or paypal.
Quick story:
I saw a 14.5" M4 upper on the EE and emailed John about it on a Monday night. On Tuesday morning I unexpectedly and in a hurry had to leave for Pittsburgh. In my rush to get out of the house I forgot my CC and only had my business American Express. When John emailed me about the upper I told him I had no means to pay until I returned home. He actually held the upper for me until the following Monday! I didn't ask him to do this but he did. I couldn't believe it. To me, that's customer service!