Deep pan or regular, with the stock dipstick the internal volume of air can be checked simply by looking at the dipstick. does that make any sense? I guess with a deeper pan the oil level can run closer to the bottom mark with less danger of sucking air thus increasing the internal crankcase air volume??
25 years ago I found a hot deal on a OE BMW oil cooler kit. I installed it on a R75/6, with the original 2qt oil pan. I would reach down from time to time and touch the cooler to see if it was working, it rarely got hot.
So I installed a VDO oil temp gauge to see what oil temps were. Most of the time the oil never got hot enough to open the cooler. On a hot day on the freeway or sitting in traffic the cooler would open a about 210deg. One time in Death Valley when it was over 120deg, the oil temp got up to 250deg. Still not hot enough to ruin good oil.
I still have the bike and the cooler is still on it, I removed the oil temp gauge long ago as I don't worry about oil temps any more. The old relic has 175,000 miles on it with no probblems, so I guess it's been happy with the oil temps.
It is a pain to change the oil filter because of the clearance issue between the thermostat and exhaust pipe, I've done it many times, it just takes alittle more time.
In my opinion the old twins don't get their oil hot enough to warrant installing a cooler.