Originally Posted by MattP725

I think your wording is off... this isn't oil coming back to the pan, it is oil leaving the pan to the block.

All in all I wouldn't see this being a major issue anyhow... once the oil is at operating temperature, the oil in the pan/block/cooler are eventually going to meet some sort of equilibrium. Even without a cooler you have to beat on it pretty heavily to get an immediate and sharp climb in oil temperature and that is generally only 10-20 degrees.