I'd second what bystander said, but add that you are now paddling a boat that is half as wide as your ik, so your primary stability has greatly reduced, which feels tippy. You have also gained more secondary stability, but that takes some getting used to. Also, your ik had nice big round edges that are forgiving and don't catch water nearly like your fun will. So, the feeling of less stability is inherent in the design of the different boats. Spend some time getting the hard boat on edges, and paddling it that way, swith edges, you may prefer to do this in the lake. Getting used to the edges, and how far you can lean without tipping will help build that confidence. Then do it on eddy lines.
Lastly, I think the stability of an ik gives you the comfort and ability to paddle rapids 1 class higher than you can in a hard boat...at least while you are learning. At some point, that switches, as you can keep progressing in a hard boat. Forgive my over generalization if someone feels otherwise. Anyway, based on that, if you are comfortable paddling an ik in class 3, then class 2 sounds about right for a hardshell.
Sent from my GT-P5113 using Mountain Buzz mobile app
"If I'm not there, it means I'm dead...or late!" General W.R. Monger