I have purchased 2 carts from Kron in the last 2 years or so. Kiseki Purpleheart and a Benz Micro LPS.
The seller is honest, reputable, and ships incredibly fast. I received both of these items in two or three days maximum from his location, delivered right to my door.
There is a downside. No warranty. I broke the stylus right off one of these cartridges. (The Benz). The manufacturer denied the warranty claim. I sent it to a third path repair facility and all is good.
I think you have nothing to be concerned about with the seller other than warranty issues. I feel the risk of no warranty can be worth it. But you should be aware of it going in.
To underscore the positive, I found Kron to be reasonable in negotiations, his shipping to Chicago was as fast as domestic shipping in many cases, and his communication was great.