OK, if there's one internet source I tend to trust on these subjects, Tanknet is the one.
Don't take offense from what I said, I just wanted to confront your info with my own data and the low-brow calculation I can come up with.
After reading the whole thread I get a better idea of what you meant: apparently DU loses its edge over tungsten in the higher velocity range (from 1700-1800m/s upwards). I have no doubt better alloys of both metals could be (or already have been) developped to withstand ETC-like MVs.