Hotspot is down perhaps 5 degrees, general GPU temps are down a little more than that on average. It's hard to tell because I wasn't paying that much attention to it prior to installing it.
The main reason was this sits on a shelf so has limited space around it except that side. I'm running case fans slower than before (were on a curve, now static at 40%) so it's a lot quieter too. Fans at the front of the case have been removed and I've got two 140mm at the top at 20% just helping air move upwards although these 4x140s push enough to clear the case easily anyway.