You and I have different ideas about diamond pastes lol.
There's absolutely no thermal paste that makes it that cold. You would even freeze acetone at that temperature.
If you value the laser etching, I get it. People delid these days. So maybe diamond paste isn't good for bare die, but I've never once had a problem.
Copper. Coolers. Lapped IHS plates.... When you clean the paste off with a towel, it shines the copper nicely like rubbing compound. It does take Lazer etching off, but nickel plating should be lapped off in my opinion. It's much worse than just saying I won't use this paste because scratches. Nickel conducts like shit. I've never seen lines like scratches, but maybe some diamond pastes have clumps of diamonds that could cause this effect. My take was when I wiped it off, it clumped in the towel and maybe left a visible line.
Not to take away from surface area. Scratches aren't horrible. I didn't have horrible results scuffing plates with 60 grit emery cloth. It seemed to work well with thicker pastes. IC diamond is thick. Difficult to work with cold. Becomes a little pliable when warmed up. Antec Formula 6 and 7 are very decent diamond pastes. I've always had good thermals, and not super thick. Worked fine both with lapped, scuffed and direct die cooling.
Been using diamond pastes about 15 years straight. I'm satisfied enough. Just like guys that stick with artic silver 5. To each their own