The foam cells do help with heat dissipation as liquid to metal conduction/convection is much higher than gas to metal conduction/convection. This is most prominent in a twin tube, but even in a traditional monotube or remote resi the gas isn't helping much with heat dissipation. There is also a much greater thermal mass to the oil in the foam cells (they are heavy). And yes, this all aids with reducing/eliminating cavitation since there isn't much gas to come out of solution due to them not being pressurized (except due to thermal expansion and the foam compression).

I've had good experience with extended washboards at high speeds with no fade, where I had previously felt the stock fade in less than a minute. I'm not running the baja or bombing through whoops in my daily. No HD springs. Most of my extra bolted on weight is in the front (skids) and mid (sliders). Drives great and is well planted when I do come across a rogue whoop (not jarring, no bouncy bouncy).