I have a max tow... and I swapped in the Fox shocks... someone was selling them for 200 bucks... there is a slight difference in the feel of the Fox shocks... smoother on washboard and such. They are a little longer... the Rubicon springs are 3/4 of an inch higher or so... so I put in spacers (1.5 front, 3/4 rear...) and went with fox shocks. It is a nice ride.
I think the shocks are maybe even stiffer on the high end, they rebound or damping is what it slightly softer in its feel.
I put the spacers in to be sure the shocks were operating as close as possible to what length they were designed for. They might have been fine without spacers... I just wanted them in the ballpark of their design.
I also have enough space to go to 35s now. Even though I'm running 33s.