I imagine that the XL will also incorporate improvements to the environmental control system; the Mark I had such a wonderful flow of fresh air through it that operations in the tropics required a warm jumper, lest the pilot freeze from the ventilaion.
................come to think of it, the couple of kilos of perspiration I shed daily when flying the broom-broom probably kept me trim in those days. Forget Jenny Craig, I'll just go back to the Sepik and fly an Islander again.