My first DP was a 2002 Holiday Rambler Endeavor. My neighbor bought it from me and still has her. I bought the "newer" PRXB Pacbrake and installed it in 2008. I did not notice any difference, so for me, it was a waste of money.
Good luck with your selection.
2019 Newmar Dutch Star 4018 - Freighliner
2006 Jeep Grand Cherokee or 1973 Toyota FJ40