Are stackable washer/dryers any good?

[Bienes Raices]

I am considering providing a stackable W/D set in the rental (due to space considerations), instead of two separate units side by side on the floor.

Years ago in an apartment I had a stackable W/D and the dryer took an eternity to dry the clothes (90 minutes to 2 hours if there were jeans in the load). Is this the norm with these units, or was I just unlucky. I don't want to provide something that's just going to p*ss the tenants off. Thanks.