I have a Carvin MB12 that has a sealed 12 on an angled baffle, 6.5 midrange & tweeter as my main combo. Sounds great for my applications, and it is versatile enough to serve for either EB or DB (or mixed) gigs. When I really need reinforcement of that lowest 1/2 octave to carry the house, I stack it on a 1X15 ported cab on casters, both for portability and de-coupling of the floor, I've had for, well, quite awhile, loaded with a Carvin Driver. If I need more than that, the combo has an XLR DI out and I use it as a monitor and let the sound man worry about it. Since all drivers in my system are from the same company, phase is not an issue, and I get compliments all the way around for tone. The extension cab is rated appropriately in both impedance, power handling and efficiency to match the combo, and that, along with staying with the same manufacturer, avoids all of the problems that can occur as mentioned in Drurb's thread: phasing, impedance matching, efficiency matching, feedback, etc.