To clear this up: I have a side edge beveler, and a base edge beveler, a holmenkol vice, a bunch of DMT stones, a gummi and an Arkansas stone. various scrapers and waxes, brushes and iron.
I think that you may have hit the nail on the head when you said that the DMT's wear out quickly, and that would be magnified by the lack of a side edge remover.
Since the side edges have not been removed, I have to position the stones so they touch ONLY the edge. This means a very small strip of diamond stone is exposed to the edge. Consequently, I think it could already be worn out, and I'm not really polishing all that much after filing away the nicks and other damage....