I've never noticed a difference between leading or lack of leading with bevel base or flat base designs. My guess would be that that a bevel base bullet would be no more prone to leading than a flat base. The only way to know for sure would be to do some extensive controlled testing.

As for an accuracy difference between flat base and bevel base cast bullets...I think this information appeared in AMERICAN RIFLEMAN some years ago when it had a technical staff and published far better articles, even handloading and cast bullet stuff. Col. E.H Harrison did many very thorough cast bullet experiments.

I believe it was a Harrison article where he concluded the bevel base H&G #68 was slightly (very slightly, if I recall correctly) more accurate than the flat base #68 in the .45 ACP. He over-tested everything and knew what he was talking about.

Mnay of Harrison's cast bullet articles were compiled in an NRA publication, "Cast Bullets". Don't know whether it's still in print, but it's worth reading.