There have been very few coding errors in the past two decades which I think a different font would have helped me catch/avoid, even with my aging eyes. I just go for legibility and fixed-pitch – and usually the system default’s been adequate.
Font can make a huge difference in some circumstances, but so far this hasn’t seemed to be one of them.
(And I’m trying not to rant about the misuse of well-defined typographic terms when applied to PC displays.)
