At the time I bought the WK2, I was not interested in having two cars, and the WK2 was a perfect combination of a smooth, solid, luxurious, well-mannered daily driver, and off-road capability for the weekends. I have taken my WK2 to pretty aggressive places and it has done quite well. The 4WD system (especially with the Quadra-Drive II rear ELSD) is quite good and with all the electronics set correctly, performs very close to a fully-locking center and rear diff.
However, it does have limited ground clearance and suspension articulation compared to a Wrangler, and there is not much room to improve that with mods - though, still quite good compared to most modern SUVs.
If your Jeep club is doing rock crawling that pushes the limits of the Wrangler, you won't be able to keep up in the WK2. If it is more muddy/sandy hill climbs, more casual stuff, etc. you should be fine, although make sure to get good tires.
The real problem with my WK2 is just that it is a very nice, luxurious vehicle, and I don't like to bang it around as much as I would a Wrangler, I try not to scratch the paint on tight trails, I keep the windows shut so the nice leather interior doesn't get covered in dust, I drive slower on washboarded roads, I try not to scrape the bumper in the dirt, etc. In a Wrangler I wouldn't care about any of that ****, and I'd have more fun. To get all the off-road equipment (air suspension, skid plates, QDII, etc.), you have to get pretty much the top of the line WK2, and it doesn't feel right smashing around a $42,000 SUV with a leather-wrapped dash, ventilated seats, wood trim, etc.
I am thinking about selling the WK2 and replacing it with a Wrangler Unlimited and some kind of sports car. That would really fit my priorities better. The fact that I haven't done it yet is a testament to just how good the WK2 is.