For weddings or other events I do, it's more than enough. Computer to USB, iPads to channels 5/6, mics in channels 1-4 as needed. I can assign my USB to whatever channel I want.
Power wise, my Bose system does power it. It's nice. I have a power cord so if I do use use it with a compact or something else, it's no problem. But the reality is I probably wouldn't buy it if I wasn't using the towers. It's great and portable, and would work with other units, but it's designed to work best with the towers.