I've got the Buckstop Classic 1 front (aluminum) and the Buckstop rear bumper and really like them both. The only thing worth mentioning is that on the rear bumper, in order to have clearance for the Aluminess spare carrier, the shop who installed it for me had to tweak the driver side just a bit and it hangs a 1/2 inch or so lower. It's only noticeable when you look at it straight-on from the rear, but it hasn't annoyed me enough to want to do anything about it in two years (not sure if there's anything that could be done anyway).
2004 EB50 SMB 4x4 V-10. Buckstop front and rear bumpers, Pro Comp 7069 wheels, Cooper ST Maxx rubbers, and a Line-x roof