The weight is a tradeoff. I don't think it would be that big of a deal in general. I mean it sucks when I get my 8,500 lb truck stuck, but often it'll get stuck less than my Jeep (wheelbase and crawl ratio, locker make my truck much harder to get stuck). However there's obvious places the truck won't fit. I think the problem with the additional weight is more of a design issue. Like swapping in an engine in a TJ that's 400 lbs more is an issue, because the axle, suspension, steering, CG, and percentage of additional weight in the front was not designed for it. A JLU is designed for it. The additional weight is probably half emissions and transmission and maybe battery related, so that's dispersed around the vehicle and everything else is designed for it. If you're doing stuff that a few hundred pounds matters, stick with pre-JK (JL weighs less than the JK) and definitely not the 4 door versions. Though a JLU diesel may weigh as much as the JKU.
If you're on trails most people will have to have enough gas cans to match the additional weight anyway to match the range. I find that in 4x4 the diesel sips the fuel much more sparingly than an equivalent gas engines. I don't have a good comparison, except with towing, but my gas gauge used to take a major hit when going off-road and now I hardly notice it. Towing I easily get twice the mileage than the 4.0, but it was also under-powered and under-geared.
In any case, if I were to get a JLU, then it would be the diesel version, because diesel is just so much better when you're not near a gas station (take a wrong turn, who cares). And it's better off-road 90% of the time (once it has been fixed from the factory). You will have more money in a diesel, but there's almost nothing I want off-road with 4 wheels that's gas powered. However, I'm not completely against picking up a gas vehicle and driving until the engine blows up and swap in a diesel assuming the frame looks like it's got hundreds of thousands of miles left on it. Of course the JLU Rubicon is priced beyond what I think is reasonable, so I'm not gonna purchase one. And I think the new stuff is a bit too complex for off-road, where screw-ups and weird stuff happens, because hey I'm not a professional driver, so I do a lot of dumb stuff and learn the hard way. That sucks when you don't have cell reception and you hit a little sensor and your vehicle won't start, which is even more true if you get a modern diesel that's not been deleted yet. If they are deleted, they're incredibly resilient and simple.
