I don't know how much it costs to own a Cruiser so it's hard to say what the differences might be.
.
In general you're unlikely to have any mechanical issues with the powertrain on the LR3. It's very robust. It's weak points are the air suspension and the complex electronics. The single most expensive component that generally can (will?) fail is the suspension compressor. Figure about $1000 from a dealer, $800 on-line, or for about $120 you can buy a kit to rebuild it yourself in a couple hours.
.
If you're really paranoid about the air suspension, Atlantic British will sell you a coil conversion kit for about a grand. You'll loose the cool self-leveling and adjustable ride height but it should have zero issues and works with all the OEM computers.
.
As for the electronics, add the cost of a GAP IId tool to your purchase price - it's well worth it to sort out codes and do your own troubleshooting or to work on the suspension (set heights, instant 'lift kit', work around a failed component in the field, etc) Figure about $400 for the non blue-tooth version, $600 for blue-tooth, at least as far as I recall. You can check prices at Lucky8, a site sponsor.
.
In technical terrain they are pretty amazing but are limited by how much tire you can run. The biggest reasonable tire you'll get on will be a 275/65-18 on a stock SE model 18" wheel. Most people actually run a 265/65 as it requires a bit less trimming to make it fit. the 275 works out to approx. 32" fwiw.
.
You can lift the truck very easily/cheaply. The GAP tool mentioned above will let you reset the height, but maybe not as much as you want. The other thing you can do is replace the ride height sensor link rods with parts from Green Oval or Johnson Rods (again, see Lucky8). These will basically make the 'standard' height the equivalent of the stock 'off road' height. Or about 2.5" of lift.
.
Aftermarket support is limited. More than anything, I'd recommend a good set of rock sliders before heading to anything tough. I'm a big fan of the Tactical Rovers sliders as they offer maximum protection. I also run their gas tank and transfer case skids and have landed the full weight of the truck on them multiple times. (I run mine a bit harder than most) ARB is the go-to front bumper, though they do stick out a bit and actually hinder approach angles slightly. Tactical also makes one, but I don't really like the look of it. You can get hidden mounts for a winch that will fit behind the stock bumper, though access is pretty tight. If you upsize the tires to 275s, you won't be able to fit a spare in the stock under-car location so you'll need to either add a tire carrier, put it inside the truck (not great) or add a roof rack (several options) and chuck it up on top (also not good due to high COG and wind drag). Rear bumpers/tire carriers are very limited. Kaymar and Tactical are about it, and Kaymar is going to set you back maybe $3500 by the time you ship it in with options. I custom-built mine based sort of on the looks of the Tactical unit but with some changes I wanted and welded it on.
.
The stock traction control systems are very good. There is the option of a rear locker with the HD package, but it can be hard to find as most people didn't order them that way. If you're not rock crawling the stock TC will likely do just fine without the locker. There is no manual control of the center (all) or rear (HD pkg) lockers - you get what the computer wants. There is no OEM front locker, but again unless you really push it you won't need it. Once or twice I've wished for one, but as I mentioned I tend to push mine more than average. ARB allegedly sells a locker but I've never actually seen one in the wild so do your research first if you think you'd want to go that way.
.
They are quite heavy trucks - mine weighs in over 7100 lbs loaded without people. I do have a lot of armor but even stock they are heavy. Power is adequate for the weight, but they're no rockets. With my 32" Duratracs I can get about 15-16 mpg highway and 10-12 mpg city. Both will be better with less aggressive tires or less weight of course. I don't recall what I got with it stock as that was a while ago and I started mod'ing as soon as I got it.
.
Figure on a semi-aggressive maintenance schedule and find a truck with good records and you should be good to go. If you want a 'drive it an forget it' sort of rig, maybe stay with the 'yota. Rovers are very much love em or hate em. Most fall in love with them, but even the newer trucks like this do ask a bit from you compared to a Camry. Still, there's something special about them.
.
Lastly, find a good Rover club in your area and hook up with them. The people really make the experience.