I finally took the plunge on Wednesday and tonight when leaving work I
fell off - am I now exempt for life, or can I expect further embarrassment
in the future?

Not wanting to tempt fate, I have had several close escapes including
uncliping the wrong leg as I started to topple to one side, just managed to
unclip in time. Emergency stops have led to the closest that I've been to
falling off. Anticipating coming to a halt and getting the uncliipoing drill
sorted has, so far, saved me from many of the indignities decribed in past
threads here.

I am reluctant to fit clipless pedals to my mountain bike. Don't trust my
balance enough :-)