We purchased the king base and have a high profile foam mattress on the base.  We've been using it for 3 months.  The ONE hydraulic arm that lifts the head of the bed is not strong enough to support much movement while raised.  If I'm in bed with the head raised, Hubby has to be particularly gentle when getting into bed as too much movement will cause the raised head to crash down.  Really not safe.  Also cannot sleep with the head raised at all as it bounces me out of sleep when Hubby turns over.  I spent a lot of money on something that's not practical to use.