I have two 6055's connected my Profilux, the fish protection works fine for me, the rotor just moves a (very small) bit every few minutes or so......(when power is at 0%). Did you set the right voltage controlrange on your Profilux "L-ports" that control your pumps(U min=3V, U max=8V) the same as the Tunze controller uses
The plastic covergrid was, and is always suppled with the 6055's, so no not cutting cost's here I think.

I have bought them about two years ago, the are the "new" ones with the blue silicon anti-vibration mounts.