I am just wondering how many miles you have on your 4th Generation. I simply don't care for the 5th Gen so I am keeping my 4th. My reasons? No interior back mirrors, no easy close rear window, no burger tray, not as bulky.
Mine has 107K miles.
I had a 5th Gen. I liked it, for the most part, and only got rid of it because it felt like the fiscally responsible thing to do with a kid on the way.
Still, there were things I didn't like. First and foremost, the lack of LSD on the 4wd system on anything but the limited. I had a Trail Premium so I could get the rear diff. MN winters call for a fair amount of 4wd driving -- most of which is on the highway for me to and from the office. On those roadways there's a ton of variation between slippery and dry pavement, and lacking the LSD bothered me. I always felt like I should be flipping back and forth between PT4wd and 2wd. It sucked not having that flexibility -- especially since the truck cost almost $40K.
There were other little irritating things, but nothing to get too bent out of shape over. I like my 4th (this is my second 4th gen) because it does everything it's supposed to do quite well -- and costs a boatload less. Mine has 87K on it, and it runs like a champ. I had to do some smaller things to make it the way I like it (lift with 5100s, spidertrax, MegaWarrior, new stereo system (the 5th gen is SO much better with the EnTune system), new wheels, new tires, and some light stuff, but at the price tag of 5th vs 4th it's worth it. Also, most of the things above would have needed to be done on my 5th too once the warranty expired (except the stereo). In fact, I had to shell out for new tires in the first 500 miles because the 5th gen Duelers were such dogsh*t.
5ths are nice, but the LSD was a deal-breaker for me. So much so that I wouldn't own another if things changed.