I'm of the mind that using Diamonds plates/stones for sharpening at the higher levels is a bit overkill for a razor, and that "normal" stones are better suited once a bevel has been established.

Using a coarser diamond plate/stone for establishing an edge has the advantage of flatness and speed, but too coarse can cause chipping. At the higher levels, the scratches will initially be deeper than other finishing stones, and then will have too little action after the stone wears past its prime.

Using too coarse a diamond plate/stone for lapping can also be a little overkill. I wouldn't use the DMT 8XX (extra, extra coarse) on anything over 1,000 grit (in fact, on a well maintained 1K, you could effectively use the 8F (fine), which is 600 grit). Using too coarse a plate/stone on a much finer stone will wear down the diamonds (and the stone) unnecessarily fast and can leave grooves in the surface of the stone. For higher grit stones, you can use a higher grit diamond plate/stone - on a 5K stone, you could use the 8E (extra fine), which is #1,200 grit. In fact, the Shapton compact lapping plate works on this theory by using different grit powders to correspond with the different grit stones. The coarse powder is about #80 grit, the medium is about #800, and the fine is around #4K. Ironically, the much more user friendly (and expensive) DGLP is a #325/375 mesh, and the DGLP is about #600 grit on both sides. I guess it's not too cost effective to be spriknling diamond powder on a lapping plate all day long.

I'm rambling now.