In reality, all 4wd and AWD vehicles should have a matched set of tires. What negates the need with 4wd as much, is that it isn't used all the time, and on dirt and other slippery surfaces the tires can slip to offset the differences in tires. With AWD, on any system really, you can't have more than a 1/2" difference in circumference from the largest tire, to the smallest. Not diameter, but circumference. Any more difference will create too much difference in turning speeds of the front and rear tires. This confuses the AWD systems into thinking there is wheel slippage. It thereby locks the system to fix the slippage it thinks it is seeing. This loads the drivetrain, just like using 4wd on dry pavement. Broken CV joints, u-joints, munched T-cases or clutch packs are common results.
With the Select-trac, and the other systems that allow a choice of 2wd, 4wd part time and full time, if you plan to run them in the AWD/Fulltime mode, you must have a matched set of tires.
The select-trac t-case(NP242?) is known for not being as robust as the NP241. For more serious wheeling, it may not take the abuse. The fulltime mode is nice on snow, but it really isn't needed. Its nice if you are on transitioning conditions, going from pavement to snow and back often and you don't want to constantly shift from 4wd to 2wd. Some members on here have it, probably not my choice, it just came with it when they bought the thing. To consider it an upgrade over a regular t-case, I guess you could say that if you think you need a babysitter/nanny nipple on your jeep to do the work for you, lol. Neither of our vehicles that we own have ABS, TCS, ESC or any of that other stuff. All I have seen it do, is give drivers a fall sense of security, leading to brainless acts while driving. If you use good sense, pay attention to road conditions, there is no need for any of it. I'm with the others, after ditching the all seasons on my jeep, I've hardly used the 4wd in the snow. The only time has been due to hapless idiots who glazed an intersection on a hill.