I borrowed one of these from Dave.c for a couple of gigs last weekend and I have to say I'm impressed.
Gig no. 1 was in a large marquee on a stage about 4 feet off the ground - a steel or aluminium framed structure which looked like it was based on a trailer. Bass player uses a Yamaha EUB through a Hartke kickback and DI's into the PA. Stage sound is normally boomy even on a concrete floor - this time it was much tighter, more focussed and the sound on stage meant we could hear everything more clearly as a result. It was an improvement from when we played the same gig last year.
Gig no. 2 was in a small pub in Ipswich (The Spreadeagle, for locals) which has recently installed a 'stage', a 6-inch high wooden structure (more of an overgrown drum riser). I was on bass, used my EBS cab (slightly larger than the pad) and Markbass head. Cab within a foot of the back wall. I've played the venue several times before and once again I think my sound was a definite improvement.
So for me, it's worked well and I'll probably buy one.
I don't understand why using a stand will reduce the amount of vibration transmitted to the floor. It seems to me that any stand capable of holding up a 2x12 or 4x10 is going to be very rigid and will transmit the same amount of vibration to the floor as the cab would. Anyone?