99.5 Pathy owner here, who has wheeled with an Xterra club for years -- the R50 is definitely lower. I believe it is a bit longer and wider... but not by much, ditto for the interior space.
That said, I can drag my Pathy anywhere the Xterras go, and I've pissed off more than one X owner by showing them up. (How I love that!!)
If you're thinking about wheeling an R50, you'll definitely want to invest in protection (skids and sliders). I have to look at my lines a tad different than the X's and sometimes I need a bit more skinnypedal to make it through (er... drag myself over stuff). Been wheeling the Pathy since 2005 (Holy crap? Where did the time go!), and she's still in good shape. Some may push you away because it's a unibody, as opposed to a body on frame like the WD21/22 - but that hasn't slowed me down. Only difference as far as I have been concerned, is that I am limited for a lift (only have the 2" AC lift), but it's gotten me by just fine.
>> AFAIK, Packie88's truck is still in WA, his parents still had it, last I heard. That was a few months ago.