I've been pretty happy with my BBT110. I recently went with an iAMP500/Wizzy rig, and while I've got the intention of grabbing a second Wizzy at some point, the Yamaha BBT110 at 4 ohms has worked great as a second cab to add some speaker area for louder gigs.
The tweeter is pretty hissy with the iAMP, but I just turn it off, anyway.
With the Yamaha on the bottom, the Wizzy and iAmp are higher up. And, when I was standing next to my rig, the Yamaha was pushing some serious air. Sounded great together. And, you can't be an extension cab for $149 shipped.
I'll probably pick up a cover for it since both the Wizzy and iAmp have them. Besides, with two cats, the carpet needs some protection when it's not getting used....