The key to maximizing thermal performance is optimization of your contact and pressure, these two simple facts are 99% of what you need to know about thermal compound performance. As a demonstration of  the impact of contact and Pressure thermal grease performance, tests were conducted by users in four different forums using Fuji pre-scale contact/pressure film from Sensor Products

The test involved inserting pressure sensitive film to record mounting force and contact area between the heatsink and CPU after installing the heatsink on the CPU. The film records pressures on the IHS from 28 to 98 pounds, which is translated into data and converted into two and three dimensional images by Sensor Products for analysis.

Combined Thermal and Contact Tests
Contact And Force Charts - In the two charts below from selected test data you will note that when contact area increases temperatures drop and when force increases temperatures also drop, the two parameters are inextricably linked to performance.

Results show that careful attention to contact and pressure can yield significant benefits and that performance requires having both good contact and good pressure.

The total span of temperatures in the sample group ranged from -5ºC to +3.9ºC, a non trivial 9ºC spread due to either contact or pressure.
Improved performance -This is indicated below in the contact images they display broad, even contact with few high spots and good pressure:
No Change - the images show uneven contact, with most of the force applied on the edges:
Alll data samples

Many thanks to those that assisted us in this effort.
  Innovation Cooling, LLC
   Contact And Pressure