Well, I will give my bike as an indicator, the serial number of my bike ends with B6385009, the 1981 model year US version of the R65 started with serial number B6385001.
So, I probably have the oldest R65 in the US with electronic ignition still on the road, so figure the sensor was probably manufactured in 1980 sometime, as the date of manufacture of my bike is : 09/80 .
I just turned 80,000 miles on the bike, and it has been ridden in the desert heat of Phoenix going on 16 years.
So I'd say that the sensor is a pretty reliable component.
But like any old electronic component, it may fail on the way home from work today !!
Availability of the part can be a problem sometimes, I was looking last August for the part at Newark Electronics, and they were out of stock, and the manufacturers lead time was about 6 months at that point in time.