I know you are happy with your setup...... and the last thing I want is to make you unhappy, but if the temps are correct I'm not convinced that those oil temperatures are that healthy.
I'm used to cars with oil temperature gauges. Some "air cooled" cars can perhaps be more more correctly described as oil cooled. Normal oil temperature would be perhaps 80-100 degrees C, and it is generally desired to keep temperatures below 105 as power starts to drop off when the oil gets much warmer than that, and then it can get very expensive. With water cooled cars, you can perhaps push to 110 but when you get to 120 you're generally cooking the engine as water temps will also have risen. Low oil temperatures are of course associated with more rapid wear. I would see 70 as being overcooled.
I did a quick google on engine oil temperatures and one of the first results I came across was this
http://www.wearcheck.co.za/downloads/bu ... tech43.pdf Never heard of them before, but it seems a decent quality read.
I'm really wondering if the readings you are getting are accurate, though I read you did some testing before fitting the sender. I don't suppose you have access to a K-type thermocouple / temp gauge to correlate the sender / gauge arrangement. You could borrow mine, but I'm not exactly in the neighbourhood. Anyway, that's my thoughts, and as you say "I could be wrong".