Got this so I can angle my Markbass 801 practice amp up in order to hear myself a low volumes when at home. Does the trick, and packs down pretty flat when not in use.
I dont think I'd trust it for larger cabs (but maybe two would be ok), but for smalller amps it does what it's supposed to. It'll work best with cube shapes, with lower centers of gravity, as larger/taller enclosures may tip over.
I've used it on a couple of smaller gigs (turns my practice amp into an onstage monitor), where I'm to close to my main amp to hear myself properly. Ran a feed out the back of my stack, into the combo and was able to get a 'monitor' feed of my bass back out to me. Bonus!