They sound great. I play through a 361 stack or a 370/408. There's never been a reason to run both as a stereo setup or with the 360 preamp running both the 361PP cabinet and 370 power section into the 408, but when it's time to cause Armageddon, that would work pretty well to do it. Moving them is a pain, but an old Chevy van is cheap and effective. A mover's blanket on the bumper makes tipping the bit ol' cabinets into the back of the van a one man operation, even if the one man is heavily reliced. The old behemoths are heavy, a pain to move, and absolutely worth the effort. The best part about them is you don't have to play loud through them, but you can.
As a comparison, I played a P-Bass and an EB-2, both with flats through the 361 recently. The sound filled an outdoor area with warm, immediate bass sound. The two instruments sounded very different, as you would expect, but both were articulate, distinct, and clean. The next band got up and their bass player played a Jazz through an Ampeg rig. It was harsher sounding. Not bad, not louder, not more distorted, just harsher. The difference was audible to me as a bass player, although I'm not sure anybody else noticed or cared. The upside of the Ampeg is it probably weighs a few pounds less. We all need exercise anyway, don't we?