First, check out these links:
http://jendeindustries.wordpress.com/2012/02/12/wicked-edge-weps-stock-diamond-ceramic-microscopic-progression/
http://jendeindustries.wordpress.com/2012/02/25/wicked-edge-weps-chosera-stone-microscopic-progression/
http://jendeindustries.wordpress.com/2012/03/04/wicked-edge-weps-shapton-pro-stone-microscopic-progression/
They are good accounts of three WEPS progressions using different stones. Tom Blodgett also does a real good job of talking about how the different grits in the progressions work.
So, Scott asked for specific experience with the Chosera stones and how the 500/10K might fit into his progression. I have all of the Choseras that WEPS offers. 400/600 800/1000 2000/3000 and 5000/10K. I do not have any of the WEPS ceramics (yet).
In most cases i use the WEPS diamonds, then “go back” to the 600 choseras and through the entire progression form there. If I am doing more of a utility edge, I go up to the Cosera 1000 or maybe the 2000 and strop form there. Sometimes I stop stropping with 6/3 micron paste (using DMY paste at the moment). On a real OCD effort I will got through the 10K chosera and stop down to 0.025 micron CBN on nanocloth.
I can get what most people would consider to be a mirror edge just going up through the 2000 grit Chosera stones and stropping. This would not make much sense if we only looked at the size of the grit claimed for the Choseras. The unified grit chart says that the 1000 grit diamonds are finer than the 1K chosera grit.
Bottom line is that there are many factors that influence the results on steel other than grit size. Tom talks about this in his progressions.
I can say that I have been very happy woith the results as far as edge refinement as well as impressive relfctivity after going up through the Chosera progression to 10K. Again I can’t compare the ultrafine cermics, but I do have the 15K Shapton stones as well as 12K SuperStones. These should be in the grit range of the cermics. Neither give visibly as pretty an edge as the choseras. As to edge refinement, I don’t have the magnification to see it, and can’t really detect the difference in sharpness with the tests that I use.
When you ask about getting an edge with no visible scratches at 30X, I can just tell you that I have never done that. I have got to maybe 90% scratch free after several hours and hundreds of strokes at each grit. I have gotten to where it is real dificult to see any scratches lokking at 90 degrees to the bevel, but shining a light along the edge using magnification, there are scratches. This, of course, pisses me of greatly!

What to take away from this? You can’t make decisions on what will work for you by looking at grit sizes. The binder of the stone, the grit concentration, the release of the abrasive, the friability of the abrasive, the creation of “mud”… all add up to make more difference than just advertised grit size.
As to the question fo using waterstones dry… DON’T!. Thye are desinged to be used wet and will only work properly whe used wet. I even use the Shaptons and Naniwa SS stones wet, even though they are “splash and go” stones… I splash them regularly. Don’t get me wrong, they do not have to be used dripping, running, sopping wet. You don’t have to use the WEPS in a tub or tray. I soak the stones that require it for 10 minutes or so, the splash and go stones for 5 minutes. By the time they are on the WEPS and arms are adjusted they do not really drip. About every 25 or 30 strokes I spritz them with a couple of drops of water. Cleanup is a matter of running some water over them while rubbing them against each other for a few strokes, then letting them dry. The mess and additional work in doing this is minimal. The results are well worth it.
BTW, I check and adjust the angles with the cube to within .1 degree at every stone change. Resetting for the Choseras is not a big deal to me. With the new arms, I can do it without even moving the slider on the base bar… If you go with the entire chosera progression, you make significant adjustments only once after the diamonds and when going back to the strops.
If your can afford a set or two of the Chosera stones, I would reccomend that you try them!
(And all of the ceramics, of course).
I tend to think, and maybe it is just justification fo buying all of this sharpening stuff, that if you have more options and take the time to experiment with them, you will be more likely to hit upon that perfect combination for each and every knife in your collection… I bet that collection will grow too..

Rabbit hole here we go!
Phil