I just recently purchased some 60mm edge b surface tail blades (EDGE 60mm CF Tail Rotor Blades Trex 450 size B-Surface LE-60_B) for my 450pro and have found them to be awsome!!!
They are very stiff and are such a big improvement over the kbdd tail blades, They are the b surface version so have some small scraches but that doesnt affect the flight peformance, they dont even look b surface apart from were it says in big letters b surface.
They feel more direct and precise over the plastic kbdd's, they sound better, look better and fly 10 times better i cant reccomend them enough!!!