Since this sub forum has been around for more than a week without any postings, I shall do what I should not do. I shall review one of my hones. If you should wonder why I should not review it, that is simply because I lack experience, and only have a set of Nortons and one Escher to really compare this hone to. You have been warned.
Craftsmanship: A Belgian being a natural hone, it has some interesting discolourations. It is, however, perfectly square. How about that for craftsmanship? It came unlapped, though. A few rounds on the glass lapping plate of my Veritas stone pond fixed that.
Resistance To Wear: Hard to tell. I have honed 20 razors with it, and there is no visual difference to its original state. I hope it will stay that way.
Coarseness: You can read up on Belgian hones and their characteristics here: Belgian Hones - Straight Razor Place Wiki. Nothing to add for me. It is a very versatile hone, as you can use it with slurry, lather, or water, provoking different coarseness characteristics with each.
Rate Of Cut: It gets my razors sharp. A feature I quite like in a hone. Using the blue side with slurry delivers very decent results. The yellow side makes for good results when polishing or touching up razors. Certainly not the fastest cutter in the world, but that is right up my alley.
Feedback: Zen-like noises. Unlike the synthetic hones I have used, it gives you a somewhat personal feedback. I like the way it sounds a lot.
Cost: Do not ask. Natural combos are very rare, and therefore very expensive. I bought this one as a token of appreciation for a 5 hour honing class I received by the wonderful people at The Different Scent in Berlin.
Collectability/Rarity: Natural combos are rare. Very rare, actually. However, they are also somewhat overrated, as you will get exactly the same results when using a blue and yellow alone, but at a much lower price.
Efficacy: If you follow the rules laid out by the venerable Bart in A simple honing method with DMT-E, Belgian Blue Whetstone and Coticule - Straight Razor Place Wiki, you will get excellent results with this hone.
I've been using the belgian stones for years and LOVE the belgian blue over all other natural stones in that grit category. I keep a couple in my kitchen as they're great for kitchen cutlery. They also are wonderful for straight razors. I use them with a slurry and they cut fast and polish smooth. Perfect preparation for a coticule.