I've done a number of mortgages and refis with Quicken.
If your situation is straight up vanilla, they're great. Cheap, quick, efficient.
However, if you you have an unusual circumstance, it totally derails them. The right hand doesn't know what the left hand is doing. It's a system, not a person, who's looking after you there.
By unusual circumstance, I mean: it's a second home, you have to change the details of the purchase contract once the application process has started, etc.
A straight up refi would probably be ok.