I did get the Dorman sensors, but I got them through my buddy's shop - he must get wholesale pricing. Best price I found was $90 at Rock Auto. I want to say the high cost is because they use gold in the connectors (seriously, not joking), but then why do they fail?
Leaf springs are holding up just fine. I haven't towed the behemoth since 2019, so I haven't maxed them out recently, but I've made several long(ish) trips towing my 4k-lb 6x12 enclosed trailer, and she still sits fine with no sag.
And the new brakes kick butt. My father-in-law, a crusty old fart (but a car guy) even complimented the truck that it looks and rides like a new truck. He just recently saw it and rode in it for the first time. Then I told him it was 13 years old with over 200k miles.