If you really care about the sound enough to fine tune it for each different venue (as you should), I would think that it would be cumbersome, at the least, to make all the adjustments at the keyboard. Every venue has it's own unique acoustical characteristics and there is no 'one size fits all' with a mix. For that reason, I would ALWAYS favor a mixer (preferably a digital one with memory in case I played the same venue a lot - for the record, though, I prefer the SOUND of analog). I've only had one powered mixer, a high-end stereo 8-channel which I still have back in the storeroom somewhere but can't remember the name (old age). I hated it so bad (because of the sound) that I NEVER, EVER used it (tried it with many different sets of speakers). Sounds good in theory but didn't work for me. My personal preference is a quality mixer and quality powered 15"s or 10"s w/sub. My preference, however, has to do with getting a good ORGAN sound without hauling a Leslie around. I currently use 2 EV SXA250's with a compact 16ch analog mixer. Sounds okay.

chas