Been running two 330's and two mp40's via the Hydros and love everything! I bought extra cages and impellers for my gyres, which makes cleaning them super easy and fast. I set for both guess is slightly more than one wetside, so it's well worth the money. I did have an issue with one gyre vibrating too much, but it was replaced for free (imperfection in the motor block).
I love that I can have the vortechs on one group and the gyres on another, but all synced through the wave engine. I even have them controlled via my apex for feed modes, maintenance modes and even programming a detritus/hurricane mode with a touch of a button. If you have multiple gyres, the wave engine is worth it, just getting rid of the power bricks and controlling them under one hood is awesome. I love the flow that the gyres produce, they're great!