, I'm in the same boat as you. I have 20s and I do some mild off-roading. When I bought the JGC the salesman was going to let me swap in 18s if I wanted them instead of the 20s. I gave that some serious
thought but in the end decided to keep the 20s that were on it. That was pretty nice of the salesman to offer that, BTW.
I figure that I'll be doing about 95-98% on-road and 2-5% off, and I like the look of the 20" wheels. In the year+ and 21,000 miles I've put on so far, I've been able to do some off-roading. One event was a 4X4 "Safety Clinic" with a local 4WD club where with the OEM Forteras and QL I came away duly impressed with the obstacles my month-old (at the time) JGC was able to do. I posted about that here, just search for it.
Hollister Hills is about an hour from where I live. The rated trails (easy, medium, hard) are great for practicing. I bought an annual pass.
Hollister Hills SVRA: Hollister Hills SVRA
Map of the Upper Ranch area: http://ohv.parks.ca.gov/pages/1170/f...anch_final.pdf
The clinic was held there, and with the club's spotters talking you through I was able to do some pretty tough obstacles. We were in the Obstacle Course part of Upper Ranch. I've also taken my rig up high to the Hector Heights Overlook a couple of times. Once I tried it when the trails were muddy but it was too slick and I turned around because the hills there are too steep and I didn't want to slide off of the cliffs.
Google hollister hills frame twister and hollister hills stair stepper and you'll see what a WK2 on 20s can do in the hands of an off-road newbie.
Also, the sand dunes of Pismo Beach are a 3½ hour drive, and the low profile 20s do okay. I did not air down because I wanted to protect my rims. Next time I go though, I will air down especially for the really soft sand.
Anyway, sorry for the long post but I think you'll do fine with the 20s. Especially with AT tires which I will get next, . You'll be able to do a lot of off-roading, IMHO. As your (our) skills and experience improve, we might want to "graduate" to 18s or even 16s to increase our capabilities, but for now 20s are fine for me.