My LPS love it. You just can't point it right at them. I have Zoas, Mushrooms, Palys, Frogspawn...etc. They all love it. As well as the Acro's and Monti's.
I have a 75g and use a 2 and a 3. I started with a 4 and it was blowing my fish across the tank. I wouldnt go higher than a 3 unless you have a considerable amount of sps.