I finally saw the black 740 today. I washed it with ONR and used Clear Seal to protect the paint on July 2nd. The car sits outside most of the time. I washed it with ONR two weeks after initially applying CS and the paint was beading nicely and still slick. Since then, either it has rained on his Monday (I wash his vehicles every other Monday), or he has been out of town and once I even had jury duty, so today (September 24th) was the first time I'd seen the car in a little more than 2 months.
The car had been washed recently at a tunnel wash but apparently had been under a tree for a while because it had a lot of sap on it. ONR had no problems cutting through it though. The beading was pretty flat, nothing like when I had washed it two weeks after initial application. The paint was still smooth and there was some slickness but I don't know if it was because of remaining CS or using ONR to wash it. The paint looked okay but no real pop left.
Since I wanted to see if it was the car's care that may have caused the less than stellar durability, after washing, I put Clear Seal on the driver's side of the hood, Opti-Seal in the middle and Ultima PGP on the passenger side. OS dried the quickest, UPGP the slowest. Visually, right after appliction, UPGP was the wettest and the CS side looked flat in comparison to both OS and UPGP. After I also cleaned their truck, I checked the hood again (about 90 minutes later) and the UPGP and OS sides looked pretty much identical and the CS side had improved visually somewhat but still didn't look as good as the other two.
Now the waiting game begins to see how the durability shakes out. Too hard to compare durability when using different vehicles, I figure it is more fair to use them all on the same vehicle.