I have a ditting ProD espresso and I want a new grinder for drip coffee.(If it can replace ProD in espresso would be better)
EK43 or versalab M3 would be a good choice to me?
(I have heard that versalab m3 is better than ditting kr804 for brewing cup. Is it true or just a joke?)

The Versalab is for espresso, not brew. My Versalab is for espresso and the Lido 1 for brew.

Marvin

I'd be pretty surprised if a M3 outperformed a well running 804 on drip.

I'm learning, much of the M3's performance is based off how good the tolerances, and assembly of your unit is. They have much to be gained by tweaking, careful assembly, and misc upgrades, ala Terranova's.

I torn mine down, cleaned it and carefully reassembled much of it today. With the same burrs (which may need changing) it's much better than before (much less axial runout (burrs closer to parallel) and it's also running more concentric (top/bottom burrs closer to center). To be honest, before it used to be really bad for drip (imho). It looks much better now. I can post a pic if you'd like. Which size of grind do you run?

No experience with the Ek43's although I'm fascinated by their burr geometry (they look great). Although they are big for home. And being designed as a bulk grinder, I wonder how much variation exists between units during manufacture and assembly (especially when running in espresso range)?

Have one that's built tight and well aligned, and on paper they look fantastic, I can understand why people rave about them. But will ALL the units be so good? Matt Perger posts some convincing graphs, but I'd be really interested to see him test 10 roburs and 10 EK's and post the average results. 1v1, tolerances can make a bigger difference than the burrs.

Just try one to see if you like it. I use mine for drip, but then again I rarely drink drip coffee.