They are ceramic waterstones, yes. Some of the hardest and fastest waterstones available.
Do they dish? Yes, but slowley. Although, I would not recommend waiting to lap these stones. Because they are very hard it can be very difficult to remove even a little dishing.
The most costly part is the need for a very good lapping plate. You could use SiC powder but it's messy and not convenient in any way. For diamond plates there are many choices, here are the ones I would recommend.
Shapton Diamond on glass lapping plate: very expensive and only able to be used on 500 grit and higher glass stones. Produces best possible texture on glass stones and flattens very fast. I was able to get one at a deep discount so it was an easier pill to swallow but I still think it's a worthy investment if you plan on going all-in with the Glass stones.
Atoma Plates: for 500 and up GS the 400 Atoma would be the ideal substitute for the DGLP. The 140 Atoma could also be used but can be a little aggressive on the stones and remove too much stone at times. Used lightly it could easily do the job though. The 140 would be the better choice if you also want a fast bevel setting stone.
DMT: the 95 micron hardcoat lapping plate is in the intermediate level of pricing. This plate is large and designed to lap most any stone without the worry of damage to the lapping plate. I have not personally used this one but it gets good reviews.
DMT: the old standby, the DMT XXC 120 8x3in stone. Same warnings as the Atoma 140 for coarseness on the stone but one of the most cost effective options at around $60. Some report the plate wearing quickly but I have one that's 7 years old and still performs, diamonds are noticeably dull but it still does the job.
To start, I would recommend the lapping plate of your choice plus the 500 and 2000 grit SG stones. The 500 is a fast but smooth cutting medium/coarse stone able to produce some very nice edges on its own. It will easily set bevels or fix minor edge damaged without the need for a very coarse stone. The 2000 is a medium/fine stone and with all the metal Swarf it spits out you would think it's faster than the 500. It quickly reduces the 500 grit scratches and lightly polished the edge for a mildly toothy but hair popping edge. From here you can go as fine as you want as they have stones up to 30,000 grit, I like the 2000 grit finish though, it's a good balance of sharpness for various cutting tasks.
I would describe them as a Spyderco ceramic that had a love child with a waterstone, similar feel but with some abrasive release for fast cutting and minimal clogging. They will also give a bit of extra polish for the given grit, even the SG500 yields a bit of shine on the bevel.
