Gave it a try about a month ago. I moved faster in kr but still got pretty laggy in spawn areas. The lag wasn't all terrible but when I did start to freeze up I had to log out and log back in to get things back to normal.
Relearning how to set macros with the new interface was something I really didn't want to take alot of time to learn either. I'm sure in the next 6 months or so it'll be a viable option for pvp.
Just to easy to stick with what you know... I probably won't use kr on a permenant basis tell I'm forced too.