Honestly springs in spring mounted bases do little or nothing, but you are correct, higher pressure does usually give better heat transfer. Really the best way to get good heat transfer is to have good TIM print in the area the CPU die/chip is in contact with it's IHS and from IHS into cooler base.
Reasons are not very complicated. TRUE Spirit 140 Power has 8mm diameter heatpipes while most other cooler have 6mm diameter heatpipes. That's more surface area contacting fins and inside of heatpipe wicking area moving liquid back to heat source and also more volume for vapor toward ends and release heat. More volume means more heat can be moved from base to fins.

Most of the heat from heatpipes radiating into the fins is cooled off in a first 15-25mm radius of heatpipe so large finpaks fin area doesn't improve cooling much if at all, and the faster the airflow over fins the quicker the heat is removed from them.

Also keep in mind that twin towers are using the heated air from front tower to cool the back tower.

Combine them all and hopefully you will understand why twin tower or triple tower coolers are often no better if as good as single tower coolers.