I just switched over to the EX-RR this month from a Euros model of 7+ years.
1st time out / Practice: I tried it right out of the box and it took a couple of battery packs to get used to it. For me the drop down was hard to get used to as I don't run a drop down normally. The radio was super sensitive, it didn't feel like I had to go lock to lock in any place but could drive with 50% throws now. I did not touch my car setup at all and the track conditions were the same as they usually are.
Official Race day - I removed the drop down. Turned the Grasper up to level 5 - for the fastest response and in the radio/receiver as well. Might as well - as it is it supposed to be one of the fastest radios out, got to try it right
Absolutely love it! Super easy to drive, and so smooth and connected. It even makes my speed control feel like it smoother also and has a lot more punch - (Orion R10.1). I even had to turn the punch down in my speedo 2 notches as it has so much punch.
Overall - Super happy to get the EX-RR!! I am glad I stayed with KO!!!