Okay, so as promised, here's a follow up after having a chance to lean on the car more. So it was a bit colder than the last time i took the car out this year (60* vs 90*), but it was another 15 degrees colder last year during the same time so I can compare to that. With the oil cooler (with just the ten row core), i was able to stay under 275* all day, where before I'd start to touch 295* 15 mins in. During the majority of the sessions I was 260 and under. The car made power all the time, except for a few instances where I'd flood the PCV due to the hard right after the big straight on this course, and interestingly enough, because it didn't retard timing as much, there was less overall fuel being used! I was able to get 3 20 minute sessions in on one tank of gas vs running 2 sessions before! This equates to about 6.75 mpg vs 4.5 mpg on track. I still think this core size would be fine for a stock car, but for stage 1 and 2 cars I'd think a 16 row would be much more applicable. For stage 2 and 3 (is38), I think a 19 row is likely a better option, especially in hotter areas.
Changing the filter is still stupid and requires covering the whole filter areas with rags and shop towels, then cleaning with an engine degreaser afterwards, unless you use the 50$ racingline filter cartridges.
Here's a youtube video from inside a friend's e92 m3 from a good hot session that day.
You can see my PCV floods twice and the car blows smoke. That section of the track i've data logged with peak G in the 1.2+ range.