Has anyone been using an ACOG on their PE90 / 550? If so how do you like it and what model have you been using?

I have been lazily looking for a direct acog mount at a reasonable price. I am a fan of the crosshair 4x acogs, but I think the 3.5x was made for a 551 contract.

I bought a B&T picatinny rail mount that goes on the top of the receiver, and should be able to get an ACOG to mount directly to it. I think it should be a good all around scope, and a pretty rugged one as well. I am just trying to figure out which one to get.