I left at my 38 (4 years ago). Leaving was an interesting time, with plenty of conflicting emotions. I approached 38 with an open mind as to whether to stay or go. PMA soon changed that, and even phoned me at home and advised me to leave (they then promoted me during resettlement and wondered why I didn't change my mind).
I was determined not to be bitter on leaving, I've always found it sad that people feel they have to slate the service to justify going. Four years on and it was a great decision, although I still find it strange the way PMA conducted themselves. If I was going to have one serious moan, it was that I was never asked why I was leaving.
Joining the RAF was the best decision I ever made, leaving was a close second.