I have a Q6600 GO @3.0GHz running at a stock VID of 1.325v. I've tried many different setups and when checking my idle or load temps with Core Temp I don't see much of a difference in temps.
My idle temps with either the push-pins or Thermalright LGA775 mounting kit are the same. My ambient is normally around 22-24C. Idle temps 36,34,28,34 and with Prime95 short FFT's running 56,56,48,51.
I could be the exception to the rule or just have a weird chip or MB, but I've even lapped my CPU, mounted the S1283 vertically & horizontally, used the Thermalright mounting kit, run 2 "push-pull" Antec Tri-cools on med. (1600 rpm) and added fans to my case and haven't seen much of a difference. I've been running Prime Short FFT's for 21 min. and my Core Temp says I'm at 54,54,47,49.
I use AS5 and it should be close to it's final curing time. I've also calibrated Real Temp and Speedfan the best I could (I can't lower CPU voltage), I figure my accurate temps are in the middle of what Core Temp tells me. About 32C idle and 52 load.
If your trying to get accurate temps from others, be sure to get the ambient, case, fan type/speed, the program they use for load temps (short FFT's are good for max cpu temps), Temperature monitoring program and if it's been calibrated or not.
I hope this helps some and I'm far from an expert. For me, the mounting kit (not Xigmatek's) didn't help my temps. I do like the mounting kit better than the push-pins, but you have to remove the MB which you already know.