It's been great. The truck has just about 41k miles on it now, so about 25k roughly on the springs. I've taken it off road, and did a long trip across the US. 0 issues, 0 sag.
I had a VW GTI years ago that kept cooking off when I would coast, but for more than OPs situation. After a few weeks of noticing it I threw an engine code. Turned out the thermostat was stuck open so I had to replace it. So it can be a sign of something wrong, even if cool isn't bad.
I just took my FX4 out to the desert on some pretty aggressive ruts and soft sand. I never left normal mode, I could watch the system feel slipping and immediately send power. I had no problem keeping up with my buddy who has a Tacoma. I'm sure if it got more treacherous changing the drive mode...
I recently had the Good Win Racing 1.25" front leveling spring kit along with their camber bolts installed.
Tires are Falken Wildpeak AT3 235/65r17. I also removed the front and rear air deflectors in front of the tires to give me more clearance.
The spring rate is slightly higher on these...
Did you need to purchase camber bolts for your alignment? The Eibach lift says it requires camber bolts to get the alignment within spec but their lift is also a little taller. Wondering if H&R is just low enough that you can get it on spec?