I installed the Thermalright LGA1700-BCF bracket, and also went from cheap ebay TIM, to some waxy TIM, TF-7 , and my temps did improve by 5-10C. Way more than lapping did. I was thinking it was mainly the TIM, I'll compare the TIM's on my old CPU someday.
I could probably tighten the bracket down more evenly, and a little less, but I tried to get it even.
Before that I also had lapped my CPU, but not the convex cooler. In the thermal wax left on my CPU, I could see the concave pattern (reverse) . So I think it made pretty good contact. I could lap the air-cooler, and my old CPU too.
Now I have a ALF2 420mm on there, and it doesn't tighten down anywhere near like my air cooler did. I never checked how flat it was either, but I'll remove it soon to see what the TIM spread is like. I'd lap that too, but it's so new, I'd like to keep it's warranty for awhile.
The TF-7 was really hard to spread, I got MX-5 iirc with the ALF2, so I should try that too.