I work at a great mid-sized (300+ employees) company that has a transparent, set pay scale, with an even simpler formula than Buffer. Each inter-level promotion is a 10% bump, and a level promotion is 20%, all the way up. I love it.

A positive side effect is that promotions become more of a "are you performing at this level?" question rather than a politicking game, and responsibilities at each level become much more clearly defined. I think that many companies could benefit from adopting similar structures.