Fallkniven's been known to have some quality issues with some of the DC3/4 hones, unfortunately. Most of what I've heard is related to finish issues on the ceramic side of the hone. I have one, and haven't had any problems with it.
If I were to substitute another in it's place, the DMT 'credit card' hones would be my first choice. I have two of them, a Fine and EF, and like them both. I'd think a Coarse might be a closer match to the diamond side of the DC4, and either a Fine or EF would make a good finishing hone in the field. The ceramic side of my DC4 is considerably coarser than most ceramics I've tried, and it leaves some pretty toothy 'bite' on an edge. Reminds me more closely of the Fine grit DMT, in that respect.
