The main issue is that the profiles which dictate the behavior of the pumps can only be fine tuned in 1/10th of second increments. While that is way more detail that one would need for anything else, for finding the "resonant sweet spot" for your tank in order to generate a wave, it's pretty limiting.
I am able to get about a half inch wave with two tunze 6100 pumps in a 5 foot tank. It's good enough for me, but I'm sure with more fine tuning I could have water splashing on to the floor. I mean if I wanted that for some reason. Heh.