My personal preference, is to use an 8" for lapping and 6" for honing. I like the 6X2 better for my hand-held honing habits.
That said: it is not entirely impossible to lap on 6". Flatness will still be accurate enough for honing razors. But it's not as convenient.
I have alway lapped on the DMT variant with the holes. (325 mesh)
I guess continuously or with holes, they both do a fine job for lapping.
One properly broken in, the holes don't interfere with honing a razor either.
Bart.