Funny you mention that, I went up today with a new setup GNU Carbon Credit also a Rocker. It wasn't as extreme of an experience as you but I noticed some differences in handling the board as well. It's certainly more floaty and high speed does feel like a bit of a different animal.
I had to go back to the basics for the first half of the day. It was weird, I managed to get back to where I was with my goofy riding. I was hopeful of even figuring out how to do butters with how the morning went. But I could not get to the point of riding switch today like I did on my old board. I ended up just enjoying the rest of the afternoon taking the express to the top and riding normally only no switch.
I'm probably not good at describing this but it felt like there was less effort required to do the same turns compared to my old board. Starting out I'd find myself body surfing instead of pressing an edge into the ground. Later on I figured out I didn't have to lean so far into it to get the board to stop like I had to do on my other board.