I'll give you a bit more advice, as somebody who built an 8.25 all the way with alloy shafts and discs, only to get rid of it because of gear noise that even a full diff rebuild couldn't cure. If you can get the 44, that is a better choice, even if you have to wait and save. I run the 34" trXus you are looking at, and I had no concerns about the strength of the 8.25. The pinion and ring gear are probably stronger than a 44 as the ring gear is thicker and the pinion is substantially larger than a 44. I'd have run 35's on my 29 spline alloy shafts, and the discs worked excellently. But the 8.25 is known for noise problems with low gears, even if the wear pattern is good.
IMHO, the biggest thing to realize with axles is that you are probably going to replace everything: most people eventually upgrade to alloy shafts with 35" tires (the 34" trXus you are considering are essentially 35's), you will replace the diff and carrier (ARB), the bearings, and over time you are going to want rear discs. So what is left? The housing. That's it.
So ultimately you should make your choice on the housing you want. If you really want the best setup, and you only plan to run 35's and aren't heavy on the gas, then a
Currie high pinion 9" is the way to go. This runs a reverse rotation Ford 8.8 gearset on a 9" housing, with a custom designed Currie 3rd member. Ford 9" parts are the cheapest of any axle. If you just bought the housing and 3rd member, you could build it yourself over time. Take set of Lincoln 9" discs and Caddy calipers with integrated parking brake from a yard, and you only need $100 more for brackets from TSM for disc brakes. Locker/gear install on the third member will be an inexpensive and easy as you will get. You'll burn some coin on the alloy shafts, but with 31 spline alloys you won't have to worry about it. I love this setup - with 8" of lift my rear driveline angle is only 14 degrees. It is amazing how quiet it is - at 60 mph I can talk softly with my family as I don't have to drown out a ton of drivetrain noise. For you...maybe that does or doesn't matter?
So look at the total cost for each axle choice. The 8.8 is popular mostly because the price of the entire axle is the same as the cost of an aftermarket disc brake conversion kit. You may be able to build an 8.8 cheaper than any other axle. You can also look for a Toyota 8" off a late model 4Runner. They are 60" WMS to WMS, which is the same as the XJ. The axle shafts are the same exact size as a 44, but the diff has 1" better clearance (think strength of a 44 with clearance of a 35). You can get one with factory 4.56 gears off a 4cyl 4Runner, with the Toyota factory electric locker. These also have the major positive of 3rd member design. I had a line on one of those for $675 delivered to my door. All I would have had to do was cut off the old mounts and weld on spring perches (the yard shipped it to another yard after I paid them, and I didn't feel comfortable that they weren't trying to rip me off, so I canceled the order or that is the axle I would be running today). The 12.1" 4Runner drums would have been more than sufficient, so no need for a rear disc conversion. The only drawback? 6 on 5.5 bolt pattern, so you'd have to do some conversion to the front. For a total build with selectable locker, I don't think you can beat the 8" if you want 4.56 gears, simply because you have no parts or install labor for the diff - you already have the gears and locker you want.
But none of that is bolt-on. Maybe you should just get that 44. I wouldn't put any coin into an 8.25, even though in 29 spline version it is a major upgrade to your 35.
Nay