I live in the land of Rye and use more of it than many commercial brewers, even at 100% rye [which I have done a few times] you'll probably never get a beer that strongly exhibits the flavors that are attributed to rye - at least by the maltsters, i.e. fruity & nutty. What you definitely will get, and eventually come to start noticing is beer that has a fundamentally different mouthfeel than rye-less beers. My perception is that the more solid foundation of a high percentage rye beer changes the flavor contributions of all the ingredients [ya, I know, that sounds like a load of psycho-babble horse nonsense], maybe like the difference between using water colors on a canvas versus on a brick wall.
As for percentages, I've done probably 70 or so brews using various amounts of rye, from my experience anything over 30% or so you're risking a seriously stuck mash without rice hulls. That's not a hard and fast rule, I've gotten away with a 60% rye beer and no hulls, and had train wrecks with 40% rye beers with plenty of hulls. I've done a few stepped mashes with attempted glucosidase rests with the idea being to improve lautering porosity, but have yet to hit the intended temp range for the rest [all the infusion calculators I've found are totally FU].
FWIW, the All Rye beers are really weird to drink, they have the viscosity of about 20 weight motor oil and the bubbles rise to the surface in extra slow motion. Surprisingly little in the way of unique flavors though.