I can tell you this, definitive proof or not, if my oil gets north of 240 degrees, I'm backing way off until it drops back down, or parking it all together. If there's even a chance that the bearings might last longer by not exposing them to those kinds of temps, I'll err on the side of caution.
I have a massive oil cooler and have never seen temps over 220, but that's probably because I'm a terrible driver.
