I have an aftermarket 2.5" receiver on my Suburban I've been using since 2014 when I bought my current trailer. I tow about 8k lbs with 1200-1300 lbs of tongue weight. I need the weight distribution bars, my vehicle is not comparable to yours, but I agree you might prefer the ride.
As for using an insert vs. getting a larger 2.5" shank, I've been using the insert all this time with no issues. I have no issues with the pin, shank, or sleeve wearing at all. I know some people have had issues with pins getting bent using a sleeve, I have not had that problem. Once it came in really handy back in 2015 when my vehicle needed a new fuel pump on a Friday night. My parents loaned me their 3/4 ton Silverado which had a 2" receiver and I was still able to hook up and go very easily. Had I had a 2.5" shank, I would have a lot more work to switch to another vehicle. It only happened once however. I can see the reasoning behind getting the larger 2.5" shank, but feel free to try it with the sleeve if you don't want to spend the money. You can always buy it later if you want.