| I gigged with the MBE150 and the larger GK112 speaker cab back in the day, and it sounded GREAT. I agree, while that little MBE150 extension cab is kind of cool, it really doesn't do what you need. The combination of that really nice combo with an external 8ohm two way, ported 112, like the new GK Neo 112, is a killer combination.
That is one of the cases where combining two different speaker cab designs really works, with the internal sealed driver providing that very nice punch and warmth, and the two way 112 expanding the low end, the high end, and the absolute volume.
I was suprised at how full and loud that little stack was. Any relatively high SPL 112 cab should work quite well for what you want to do.
WARNING: For some reason, many of the MBE combo speakers were wired backwards (i.e., the positive and negative wires switched around). As long as you are just using the internal speaker, it really doesn't matter. However, MANY have reported out of phase issues with this little GK combo when adding an external speaker (i.e., the volume and low end will actually DECREASE when you add an extension cab, due to the polarity mismatch causing one driver to piston out while the other driver is pistoning in). If this happens... it is a minor issue. Just reverse the speaker wires on one of the cabs. Just FYI, since it happens quite a lot. | 
