That first question is a doozy to answer. Byram didn't look as good as he does with Dahlin while Dahlin was out. But he certainly didn't look BAD while Dahlin was out. Byram plays with Dahlin better than anyone that Ras has ever played with, so that's gotta count for SOMETHING.
I'm not sure Byram is a legit top-pair guy by himself, but he and Dahlin are a legit top pair. He's certainly a legit top-4 guy on most any NHL team and if the chemistry is right, doesn't look out of place as a top pair guy.
The way those two have looked together, particularly since the 13-game abomination.......I'd love it if we gave Byram the same deal we gave Power and then dealt Power for that two-way C we desperately need (though, Cozens does appear to be playing MUCH better). Power has the higher ceiling (still), but Byram is more consistent and far better in his own zone.
How good can Bo be in his prime, if he maxes out? A very good, borderline-elite two-way consistent guy. Not necessarily Norris-caliber, but still pretty damned good. Maybe a souped-up version of Hronek?