I've never given a second thought to 28 tooth cogs with SR & NR ders. Thousands of miles in the Sierras with that setup, tackling long 17%+ climbs, no problems, although, frankly, I don't recall whether I used to cut the chain too short to run big-big. I might have.
In my dotage, I am grateful for modern triples.
Peter Bridge
SDCAUSA