I like my dmt extra coarse, but I don't have the more expensive diamond plates to compare to. One thing is that a finer dmt is nice to lap finer stones
Depends on the knife...I have some finger stones that are pretty fine that would do well for traditional knives, and they are pretty cheap.
If you are going to buy from Maksim, get a 1000 Matukusuyama (http://www.japanesenaturalstones.com...-matukusuyama/), and pick up an inexpensive
I hope you are well.
I hate being that guy, but...
Level concrete sidewalks with plenty of water works faster than any lapping plate you can buy.