[quote author=Reefdad link=topic=6459.msg83059#msg83059 date=1235162964]
I guess the real question is, is the vortec system enough flow with just a wave pattern to sustain LPS or any other corals with high flow needs?
[/quote]
If you went with the MP40, then probably yes. However, I wouldn't rely on the Wave mode. I started off using the Wave mode when I first put the MP20 in my 28g tank. Although it looks pretty cool, my LPS's didn't seem to enjoy it much. It wasn't until I put it on Reef Crest mode that I got better polyp extension.
If you're considering the MP20 versus the MP40 based on price, then I would get the MP20, and just try it out on your tank. If you need more flow, I've read that you can upgrade the MP20 to a MP40 by purchasing the wave driver.