@ Chewie: With all due respect, I think you blew it. Cougars are just nicer guns than M&Ps, except for maybe carry. All you needed was a couple new mags. But I guess that shouldn't have to come out of YOUR pocket, so maybe you have a point.
@ jimmythegeek: My favorite auto now, CZ 97, has the mag release far enough forward that one would need longer thumbs than I've got to release it one handed,
without changing my grip. You just have to rotate the gun a bit toward your thumb, being careful to keep it pointed down range. The Beretta 92 grip is smaller than that of the CZ 97, so this technique will work for you too.
@ Marquez: Yes, same action as the PX4. The Cougar came first, by Beretta. Then, they went to a polymer frame, called it the PX4, and sold the Cougar to Stoeger, who is still producing it with great success now. I bet Beretta even sold the tooling to Stoeger, so the only difference is that the tooling was newer when the Beretta Cougars were made. (maybe slightly tighter tolerances on the original Cougars)
@ FLYMRY: Your 92 will go back to being your favorite when the honeymoon with the 84 is over. Why? Ammo cost. If you really like the 84, get into reloading so that it isn't so crippling to shoot it. Reloads cost about $8 a box for me. They take very little lead and powder, so the hardest part is not losing too much brass when you take it to the range. It looks an awful lot like 9mm from 5' off the ground.