I've had experiences with both MTM online and MTM retail before (plenty in fact). I can understand the concerns that people have with trying out MTM online for the first time, especially so if its a tailor that you have never worked with. I too, felt the same.
While browsing through Ethan Wong's blog, I noticed that he mentioned about a tailor in Vietnam that made a rather vintage looking suit for his friend. Of course, the vintage style was based on the request of his friend but I thought it looked pretty good!
I reached out to him on Facebook and decided to decided to make a suit with him, as there was a 20% promotion.
Chose a navy VBC (Wool/ Linen) fabric. Sent him my measurements and photos of my body (front, back, side). There wasn't a fitting session per se but he would send me photos during the process. The first suit turns out ok. The pants were quite spot on but for the jacket, I had to bring to a local tailor to make some adjustments.
Snapped some photos for the areas to adjust and sent it to him.
Made another 6x1 jacket with him and this time round, no adjustments are required. Turned out pretty well, and better than I thought it would be. Not perfect, but good.
Thought its good value for the money that I paid for. Probably the only online MTM tailor that I will go to.