Bought a Zulu Grey last year, loved it, didn't love it, put it away for 8 months, took it out again, lapped the backside with loose grit and left it at that texture, now I can't stop using it.... great hone, great finisher/polisher and this particular stone is fast, compared to my other naturals.
Good natural hones are great, so are good synthetics. I revisited my Naniwa 12K as an experiment to see just how good an edge I can get off it now. It's really nice, not quite as nice as perhaps a couple of my favourite naturals, but plenty nice for shaving and much faster. One thing I have noticed though.... I always seem to get a synthetic hone right off the bat, naturals have this on again, off again sort of thing until I figure them out.
My advice.... When you just cannot improve on the edge from a good quality synthetic hone (with very little to no work on pasted strops), and you are starting to feel bored, that would be a good time to think about playing with naturals. They will not instantly improve your edges... they take time to learn, and if you have already figured out how to eke every last bit of sharpness/smoothness out of your synthetic, a natural can be fun to play with and you can always get a great edge off your synthetic if you are having some issues with your natural.
There is no *instant* gratification with natural hones (well... maybe with one of those thousand dollar+ Jnats), be prepared for a learning curve and possibly less than great edges... GSSixgun's tag line is accurate and true:
"No amount of money spent on a Stone can ever replace the value of the time it takes learning to use it properly"