How long does it take? Who knows -- we put a load in when we head out sightseeing in the toad, and when we come back hours later, it's done. Can't do that in a stack! And if they're wrinkled, who cares -- we're retired and traveling.
But seriously, there are tradeoffs, of course. The combo gives you the aforementioned "one stop shopping," which for us is a big advantage, plus the space savings. The stackable gives you the ability to overlap 2 loads (one washing while one drying), if you're there to swap them out, and somewhat more capacity (or so I hear).
Different strokes for different folks ...