The Pioneer is way better then the BR. Not only in looks and suspension but many other factors as well. The independent, rubber mounted sub frame of the engine makes for a smoother ride. The redesign of the frame and positive rear end make for a awesome machine while maintaining size. You cant find a shorter wheel based 4 seat sxs on the market. It incorporates a new controller that auto chooses between aggressive mode and sport leisure mode for when you just want to cruse around. 4x4 with true diff lock will get you out of most any situation. Not to mention the 2 rear seats of the P4.
As far as capability. It surprised me this past weekend. After seeing a Yamaha running 28's get stuck this weekend I was afraid to try the same hole but when I did the Pioneer tackled it like a small puddle.
The Pioneer will follow any other unmodified SxS anywhere. However, if you are wanting speed. You should look else where as it tops out at 45'ish. But if you want to pull a loaded wagon down the trail, the family around the farm, or a Polaris back to the truck the Pioneer is your only choice.
They all have there fun factor and all differ in ways. You will have a blast no matter what you choose. Overall, you have to make the decision on your own. It was a hard choice for me and I am glad I chose to go with the Pioneer.