Having just returned from visiting my adorable GP, I find a wealth on input - as so often, and, as always, appreciated!
The M1 option: the pattern, in a different part, calls specifically for m1r and m1l; so the designer seems to have had a specific ... ahhh ... idea in mind with regard to directing the unfortunate knitter to these two differing methods of increasing.
I, being - as we all know - a virtual tyro in terms of so many things about today's knitting, feel myself impelled to follow the directions with unquestioning obedience. But when it came to the pfb, I gave up.
I did pbfs, instead!