I traded in a 2011 GMC Sierra CC w/ 6.2L for my Hemi powered Overland. There was around 50K miles on my Sierra when I traded it. I am happy to a degree, but also have some regrets. The Sierra for the time I had it was completely trouble free. Just standard maintenance was ever preformed on it. My Jeep only has 8k miles on it currently and it has already been back to the dealer for two recalls and issues with Uconnect (with a third recall on the way apparently). The fit and finish on the Sierra was also better in terms of alignments and such. That's actually my biggest complaint on the Jeep - trim pieces falling off and misc. interior pieces looking out of whack. I do like the Jeep's size for where I live better (Boston, city). I also really like the 5.7L engine mated to the 8-speed transmission, however gas mileage is just as poor as the 6.2L was. I thought I would get slightly better with the slightly smaller engine, but no dice. I get around 13-14mpg in the city and 19-20mpg highway, which the 6.2L did. In terms of comfort they are about the same. My Sierra was an upscale SLE with leather, navigation, auto climate, etc. just as my Overland is. I do think the seats in the Sierra were more supportive, but the Jeep's are comfortable as well. I do miss the truck bed sometimes, but overall the Jeep's utility works for me 90% of the time. Towing wise, both tow my boat with ease, so no issues there.
To sum up, knowing what I know now, I think I would rather have kept the Sierra. It was trouble free, same on gas, and just as comfortable. Honestly the only advantage of the Jeep is its size in the city. The Jeep does have a few more bells and whistles (blind spot monitor, ACC, heated & cooled seats, heated steering wheel), but these were all easy to live without. Not trying to deter you, just giving my honest experience and opinion. Best of luck in your decision.
-Eric