another con that applies to rusty rigs is that the weld between the sheetmetal and tube tends to rust, weaken and split apart after a while, especially if the backside of the weld inside the Jeep isn't painted or otherwise treated. not a deal breaker, but important to keep an eye on.
I almost went this way with my 88 but decided to a more traditional rocker guard welded to the frame after realizing I had very little clean metal to weld to in the rocker area.