I purchased my first vintage watch from Analog Shift last week. The entire process was a pleasure. Jake was extremely clear and helpful in communications. The watch was advertised well and came as advertised in excellent packaging. I wouldn't hesitate to buy from them again, except that price is probably higher than one might be able to find at auctions and by doing one's own legwork. For me, the discretionary spending was well worth it.
Also recommend them. Very welcoming and a solid collection. No, not for the price-shy, but often tracking with condition.
They're great guys, and their mark-up is no different than buying from any other vintage dealer in the high-end space. Probably my favorites that I've gotten to know over the past few years (although I don't buy from dealers, so I haven't given them any business!).