I met Kron in one of his seminars in Rio, and he was nice to me. But yeah, he can be really cocky and rude. He's that cool friend that is cool to hang out with, but that is the bully of the school that makes fun and pick on everyone but you. He was nice to me, but he was really disrespectful towards some old school black belts there. He cussed a lot during the seminar, didn't seem very patient and when someone would ask him something like: "how can I pass the x-guard?" he would be like: "thats a dumb question, show it on me". The blackbelt would put him in the x guard, and obviously he would pass his guard with ease (after all he is a top notch competitor, and the student is a 40 year old black belt that trains BJJ for a hobby). He would say stuff like: "you have a sh***y guard" or "you are a black belt and you don't even know how to pull guard?"
if someone asked him if the move could be countered he would say something like: "you are the sh*t right? so come and do it in me, let me see if your counter works"
I was really surprised.. Everyone from Gracie Tijuca got pissed at him, and he is for sure not coming back. It was still cool to hear his insight in some things, even though he isn't really a good teacher (he is not patient at all). I wouldn't be surprised if he had actually cussed students out in his gym. I mean, if he did it with black belts from a different gym, imagine how he would treat his own students in a bad day?
I also heard from another dude that he almost started a beef with a black belt from Gracie Humaita in Rio after rolling really hard with him.
I would still want to check his gym out.. just not sure if I would want to train there full time.