I have both the Fallknivven DC4 and CC4. Both stones are well made. But the quality can vary. So you could be unlucky and get a lemon (is that the correct term?). At the beginning the dark ceramic is quite rough, but gets smoother and finer when used (and can be lapped finer with a diamond stone). The edge is not bad.
The diamond side looses its coarseness rather quickly. And the fine white side (CC4) will leave a very sharp edge.
I like the DC4 / CC4 dark ceramic more than the Spyderco Medium, because in my option it works faster. The Spyderco Medium will already make an impressive edge but needs much more time when the edge is more on the dull side. And - as already mentioned - the Fallkniven ceramic will give you a very sharp edge, too.
Or - as a budget stone - you could buy a DMD stone, like this one
DMD-1828. The ceramic side needed some lapping (diamond). But now it leaves a super sharp edge.
Another option could be a EZE-LAP CD4
EZE-LAP CD4. Or one of their EZE-FOLD sharpeners
EZE-LAP. I do not know the CD4 first hand but I used a Hone & Stone Super Fine. The diamond side was well made.
Tried to insert some images of my pocket stones.
From left to right: DMD-1828, Fällkniven DC4, Fällkniven CC4, Coghlan's Sharpening Stone.