Couple comments from me and my experiences over the last decade and a half with the ARB and the Tru-Trak. Tire wear is the same on the back and front. Diesels are tire eaters anyway, lockers or open diff. Nature of the engine ant torque. I pay no attention to that.
My fuel mileage with my Ford has always been good so long as I keep my road speed below 68. Over 68, it goes south pretty quick, 4:10's are deep gears.
My truck does things other than tote a truck camper. It's a farm truck and it hauls around a tandem axle gooseneck that is usually very overloaded. I'm a typical farmer so the fewer trips made the better. I've loaded 20K plus of round bales on the trailer and went down the road before. You need deep gears for that kind of abuse.
I like the 4:10's off road in 4wd because my low range is so low you can walk faster but it has all kinds of power and I'm not in a hurry anyway. You get in a hurry off road, it usually turns into carnage time. Fools go fast, only fools.
I run a Lewis Winch because I always have a chainsaw with me along with other tools as well. You never know and the Lewis uses my Stihl Chainsaw powerhead. I think I've used it one time but I was glad I had it. It only takes one time.
Never an issue with the ARB. I had reservations about the air engagement/disrengagement but it's been trouble free and I use the 12 volt on board compressor that keeps my bags aired to actuate the ARB. The Detroit has been without issue as well. I did have an outboard seal issue with the corporate 10.25 rear axle but it was my own doing. I got mud in the vent hose and the differential couldn't vent so it vented the way of least resistance, an outboard seal. It was brake time anyway so I replaced both sets of rear shoes (my truck has drum brakes on the back, remember, it's a 1997 and 2 new outboard seals went in too. Easy-Peasy with a full floater. I re routed my vent line so hopefully it won't get mud in it again.
I've had no problems with either and the rear especially has gotten me though some stuff. I have a creek crossing to negotiate to get to my property in Northern Michigan and sometimes it can be, shall I say dicey, especially with the camper on.
I have toe stock diff covers, always did. The rear cover has no provision for draining the hypoid oil but I haven't an issue pulling the cover to drain it anyway. Gives me a chance to inspect the works.
I change my differential oil every 2 years (same with the E4OD fluid and filter, no matter how few miles I run. Oil is cheap. I get it in 5 gallon pails anyway. The exception to that is if I do submerge the wheels to the axles, then, when I get home, they get drained and refilled and the front outboard wheel bearings get cleaned and repacked too. That only happened one time that I can remember.
Very happy with mine. Was a good investment in 1998.
BTW I still run the OEM 16" Alcoa Forged Aluminum wheels. Work for me. Besides, after stripping them and polishing them to a mirror finish, I'm not about to change them but then I carry a pop up, not a hardside so my weight is well within the capabilities of my tires, wheels and cargo capacity.