Finally got around to installing the stuff in the rear. Put in new control arms (upper and lower) and Bilstein 4600s. Despite the appearance the old shocks still had some life left in them - not totally shot at 160k miles, although the rebound was probably 50% slower than the new Bilsteins. Old control arms probably could've been reused - which would cut the job time in half.
The job wasn't terrible, and was about what I expected. With my wife's help, I did it in ~3 hrs, including a tire rotation. The 2 most annoying parts were accessing the top shock bolt and nut and then reinstalling the fender liner. A cordless impact made short work of bolt removal, and we were able to use a crescent wrench to hold the nut for most of them. That wouldn't fit on the top shock bolt so we had to very awkwardly cram a breaker bar and a deep well socket in there. A 21mm stubby wrench would have made the job far easier but I didn't have any that large.
As for ride quality, high speed impact control is greatly improved. Far less crashing/bouncing over bumps at 50+ mph. At lower speeds there's a moderate improvement - mostly in the noise department - no more creaking over speed bumps, but it is a little smoother. I'm glad I didn't go with the 5100s, I wouldn't want anything firmer than these. Overall the 4600s are roughly on par with the [aged] factory Z71 suspension comfort wise.
Did not replace the jounce bumpers as I couldn't find them in stock, but mine looked pretty worn so it might be a good idea to replace those at some point.