[mgdlbp]

Huh, I'd assumed that ink traps would somehow be absent from fonts intended for screen use. Thinking about it now, though, it does make sense that (at least on typical computers) it's the same font file used on-screen as sent to the printer, and at small sizes on-screen they're probably hidden by hinting anyway. A cursory search also reveals that varying paper and ink conditions made for an age-old problem of achieving consistent weight.

And indeed, the distinctive spur of the 'R' all but disappears at low optical size. Something else I never noticed: the spur of the 'a' changes from vertical to horizontal at high weights in many grotesques.