There is a lot of people that uses MX-4 because is good quality, easy to find locally, and is not electrical conductive
If you want a better one use the thermal grizzly kryonaut, the difference of temperatures with the MX-4 is not going to be much though
The biggest temperature reductions are achieved by either delidding CELL/RSX (this is a dangerous process), or by using custom fan settings (there are several means to achieve it)
With CFW you can use some apps to patch stuff related with regions in RAM, im not sure but i guess this is what some backup managers does
The other way is what i was mentioning... at the roots of the PS3 are stored that identifyers for regions (secured in encrypted areas and together with a lot more tenths of settings, because sony doesnt wants us to change them), i dont remember to read any mod to modify that, but well... this is still a work in progress, ther are many stuff labeled as "unkown" that we dont know how it works yet, so eventually you could be able to achieve what you was asking for: modify the settings, then install OFW (and the settings should remain modifyed forever)
Most probably you are not going to return to OFW though... the PS3 homebrew scene is addictive