It's time for a new lapping plate and I'm at a crossroad. The common $50 lapping plates work, but I've been thinking about stepping up. One of the $380 models boast a +/- 5 micron diamond size tolerance. I spoke to a dealer who said that the surface of your stones is only as uniform and flat as the lapper. Meaning that if the size of the diamonds in the lapper varies more than of my lapper, I'm not taking advantage of the stone I paid for. So, we get down to microns, which is a problem for me, and here's why:

If I was sharpening completely flat blades, I'd be pulling/pushing them flat all the way up through the progressions, and a perfectly flat and uniform surface would be ideal. But I'm not, I'm often sharpening slightly rounded blades (smiles, etc) with a X or rolling-X pattern. With this in mind, just how flat and uniform do my stones really need to be?

I know that uniform flatness is very important when grinding and setting bevels, but when you get up to 10-20k, and start rolling, everything changes. Whats your opinion?