You'll notice a little more self-centering tendency of the steering in 4wd with the Trutrac, but nothing severe.
I love the Trutrac in the front of my TJ, and if I was using my GMC more offroad, I'd put one in it too. They work especially well in vehicles with solid axles, where the tires stay in contact with the ground better than on IFS vehicles. Once you start lifting tires, it takes a lot of brake modulation to keep moving well. Better application for a true locker...
I've installed several differentials exactly like the OP did, even in Dana axles. I swap the shims over and toss it in, and I have yet to have to pull it and re-shim to get a good pattern/backlash. Actually, I usually don't even check the pattern, I just make sure backlash matches the diff that came out and I know the pattern will match.