I have one. Bought it about a year ago when I upgraded Project arm to EKOS SE. I previously used an Adikt MM on the Project arm. I have Keel, Radikal, Tramp. I bought the Krystal after demo on another similarly equipped LP12. There's no comparison to the Adikt, since that is a MM cartridge. I believe the overall tonality of the cartridge is great. I listen to jazz, alternative, new age/downtempo and have been pleased with it. My initial take wasn't that good, but I gave it 150+ hours and I'm glad I did. There was a moment where the detail and speed became significantly and noticeably better. Then, at the suggestion of an experienced audiophile friend, I replaced the Linn tonearm cable with a used Audioquest Leopard ($500 on AGon). That was almost as noticeable improvement as upgrading from Lingo to Radikal.
Do I think Krystal is the best cartridge in the price range for the LP12? No, but I also drink the Linn KoolAid and believe their products have a certain synergy. it's so hard to demo a specific cartridge on your gear, my answer is based on what I've heard other cartridges do on other TT. I cannot get my local Linn dealer to install non-Linn cartridges on their demo LP12 for me to make a better comparison. Your taste in sound and how your equipment processes it might lead you in a different direction - e.g. I really like the Lyra Delos at this price range, a bit more detailed and crisp than the Krystal, IMO. My Linn guy runs a Dynavector XV on his personal LP12. So that tells me something. I've heard the Lyra Atlas and it's wonderful in very respect, but at a price. I am also awaiting a listen to the new DS Audio optical cartridge/phono preamp combo. My friend went to Munich and he said it was really special.
Now that I know, my recommendation would be to patiently listen to as many cartridges as you can (even above your price point to hear differences) and try to eliminate as many variables as possible so you're hearing the cartridge itself.
Good luck and enjoy the process.