Other than the cost of big reservoirs? Any upsides? I'm leaning towards a bunch of 2X4's, cuz I can source the ressy's for $13 at dePot. But then when you start to get into double digits, the need for so many pumps and timers means more links in the chain - and more opportunities for failure. But on the other hand if you have big tables, you have a lot to loose if one goes sour for some reason. I guess it would be sort of silly to have a gymnasium full of little 2x4 tables. Not that that's what I'm going into but still.