What does 80mm limit me to in a suburban bortle 5/6 skies?
I will assume that the skies are genuinely Bortle 5/6, which is to say that all 7 main stars of the Little Dipper are readily visible even when the Little Dipper is pointing down, that the summer Milky Way is obvious overhead but perhaps not down near the horizon, and that M31 appears small and fairly faint to the unaided eye.
That roughly matches the conditions where I did the suburban observations for my Urban/Suburban Messier Guide. Under such conditions most of the Messier objects are obvious to the experienced eye through an 80-mm scope, and the brighter ones, including most of the open clusters and a few of the nebulae, show significant detail.
You would get a significant though not Earth-shattering improvement going from 80 to 100 mm. But to get significantly better views you need a LOT more aperture -- which is to say, not a refractor. Through an 8-inch scope all the Messier objects are obvious under such skies, and almost all of them begin to take on a real life of their own. In particular, a fair number of the globular clusters begin to resolve into individual stars.
This is why it often makes sense for the photographic instrument to be different from the visual instrument.