I've only run the v3 Rumbles (200/500/800HD) and my Traynor Small Block 200H through a Rumble 210. It's never disappointed me. The cab itself can easily handle the power of an MB500. As for the tone I'm a huge fan of Eminence speakers in general and especially the 10s used in the Rumble cabs. I find them to have real smooth and forward low-mids while handling the rest of the frequency spectrum with ease.
They love volume too. Giving them a good boost of power really lets the low end come to life and fill the room. I even use the tweeter which made a big difference in bringing clarity and presence to my effects.
As for weight there's a handful of cabs that can kinda match the price:weight ratio of the Rumble, but at least in my searches weight-wise it's on the light-ish-side. Though if weight is a chief concern I believe that the Traynor and Trace Elliot 208s, along with the Ampeg SVT210AV are all around 25lbs. None of those have the power handling and sound of the Rumble but they're as light as you'll get before going to something like a Phil Jones cab.
I say get the Rumble (obviously lol).