You will pick up some good mid range power with the slip on. The full pipe will probably net you a little more top end power but most likely sacrifice low end. The larger head pipe will probably reduce beackpressure a lot.
I dont have any advice for you guys on the DG setup, but if you do make sure you post some videos. I have not seen any on youtube yet. It is a good resource but there always has to be the first guy to make the leap of faith!
I know that no one makes aftermarket A Arms for wolverines. I went down the wider offset rims and wheel spacer path and found it takes much more steering input to ride it. This is due to the increase leverage the wheel has because the tread is further away from the fulcrum point (ball joints)...
I am looking into Douglas (DWT) rims. They are a plain silver or black aluminum wheel that they make in a 12 X 6. If I can find them in a 5+1 I think it would be very similar to stock.
The rear brakes on quads usually don't last very long anyways. Everyone I know replaces their rear pads much more often than fronts. You have to think that there are 2 calipers up front and only 1 in the rear so it takes more of a beating.
I cant imagine it would cause any trouble other than placing more stress on the rear axle, which should be a problem. I know when I had the aftermarket wheels on mine the fronts were spaced out farther than my rears so I also had to run spacers on the rear to even it out with the front.
Like you say I am sure the carrier can handle it but I just don't know about the truck. I think most hitches are only rated for 300-400 lbs tongue wieght.