The MC286 frames arrived earlier this week.
The total time from placing the order to arrival at my doorstep was a little over 7 weeks. Most of that time was the custom paint job. I was warned it would take a while, but it took a little longer than I was planning. After about 5 weeks, I emailed my contact at Miracle Bikes asking about the status. She sent me a photo of one of the completed frames, and a couple of days later sent me a shipping number. The shipping numbers can be tracked by the US postal service, but often there is a lag (in this case close to a week) between receiving the number and the USPS tracking system recognizing it. The time from receiving the shipping number to arrival was just over two weeks, so I imagine a buyer not wanting custom paint could receive a frame in less than three weeks.
The bikes look great, a nearly perfect rendering of the artwork I sent them, and the quality of the paint looks really good. The through axles I had added to the order were already installed in the dropouts. They seem to be specific to this frame design (which is also the consensus on this thread at mtbr.com), any prospective buyer is advised to order them with the frame. I didn't think to ask about it during the process of purchasing the frame, but headsets were included. I'm waiting for a few more parts and then will be ready to start assembling them.