What a great letter straight from the horse's mouth.
My 16H has caught fire twice when trying to start it and patting away under the petrol tank with my glove isn't my idea of fun, hence I now have a gauze flame trap fitted.
One breakdown out on the road in 28 years (gearchange return spring), starting out with a bike that was already 45 years old is a pretty hard record to better...
I've done the workshop time to achieve that level of reliability but you can't achieve it at all without a design that is basically 'sound as a pound', which the M20 is..
I would put up my M20, with confidence, against ANY WW2 military bike in a long term reliability test...