I have lifted 3 of my own Super Dutys and maybe a half dozen others. I have used BDS on all of mine. I recently helped a buddy do his truck with a pro comp 8". We fought the track bar on this truck for hours. Never had this problem before. So finally after referring to pro comps instructions, they call for alignment cams and smaller bolts then the factory hardware. These bolts take a lot of stress and are torqued to 150 lbs. After we got it together with the pro comp hardware. The truck was drastically leaning towards the drivers side. (and yes the cams were adjusted so the bar would be as long as possible). After playing with it some more we even noticed the leaf springs were pulled all the way over to drivers side of hangers. We finished putting the truck together and he drove it that week.
I decided there has to be an issue with that bracket. The pro comp bracket is the same for the 6" and 8" only difference is these alignment cams (so the bigger truck gets the weaker parts) Heres one reason why pro comp sells their lifts so much cheaper.
I convinced him to order the BDS bracket. We pulled off his pro comp bracket and swapped them. Look at the difference in height, quality, and hardware.
(the bolts already rusted in 5 days)
The BDS bracket fixed the problem!
Another thing worth noting is Pro Comp uses the same leaf springs front and rear for the 6 and 8". The difference for the front is the 2" hanger shackles. The rear is they give you one more block. That's right I said one more..... Pro comp wants you to stack two blocks on top of the factory block (3 blocks). I don't know about you but I would never put that crap on my trucks.
This is just my experience with pro comp lifts. I know I wont ever run one. It's worth the extra money to get quality parts.