I got to try this out on loan from someone who is trying to sell it. It's really not as bad as some of the reviews I read. I would say it focuses as fast as the Quattro in most circumstances, maybe a bit faster with some lenses. I got a 70mm F2.8 with it. I really hard a hard focusing that lens on the Quattro. It was pretty snappy on the Merrill. It's exceedingly well built like the Quattro. It has the quietest mirror box I've ever heard.