I am late to the party here, but I have an opinion I'd like to share.
I can't say I've paddled NZ, and I dont know how your big water styles compare to the US Colorado creeks and rivers here, and I cant say I've paddled any class V rivers, mostly class IV creeks and low volume rivers. ie, gore under 1100cfs. so...
I did learn a while back that If you paddle a creek/river boat with a similar hull design to your playboat that there is less transition from one boat to the next. I have a super fun for a playboat and a L karma as a creeker. They feel the same going in and out of eddys on edge, the speed is not there in the PB, but I am doing well in this combo.
I had a villain L and a superfun, I get what people are saying about displacment hulls on creeks tho, my karma requires more attention than the villain on rocky runs, I get that now.
But if anyone is a class V boater I bet they could paddle any combo boats they like, put a medium karma on your demo list, I think you'd like it.