I just checked the DMT website and indeed, I was correct on the flatness claims:

Here's a quote regarding the D8 series (8 x 3)

"The precision-engineered surface flatness to + / -0.001” will remain flat forever, offering the sharpest edges with no maintenance."

and in reference to the coarsest stone:

"With a surface flatness to +/- 0.001" Double-X is perfect for flattening water stones, Arkansas stones, and synthetic stones."


Now, considering that +/- 0.001" over 8 inches is pretty much the standard for basic machinists squares, it will have no discernible impact on razors or flattening hones. There is of course always the chance that a defective hone might get out and if so I would expect DMT to make it right. Personally, I think the D8 series is one heck of a bargain.

Regards

Christian