Hey, I have this tank and the gyre fx150, in my opinion is definitely good flow for the tank. Aquascaping of course is a big factor in determining the usefulness of the flow pattern. My aquascape is quite open for now. I actually had to remove my sandbed in order to run the fx150. Even on 30% the fiji pink sand I had was storming around constantly. I only gave it 3 days before I decided to just take it out. However, I did keep a light layer of sand in there which has since accumulated in the back pockets of of the tank. I expected this and left it there as sleeping dens for my wrasses!
However, since acquiring many sps pieces and becoming more interested in TONs of flow I also came into getting an MP40.
I believe I will place the gyre on the side opposite the overflow, since it is the widest, and then put the mp40 on the smallest side, with the overflow.
That along with the return pipes facing towards the deadspots right below each pump should work well in moving waste off of the floor.
And, yes, for me, I would say that the DB does scratch fairly easily. Very light not really noticeable, but I have to be very mindful as I clean the class.