I used Doug Fir on my last kayak and it was very split-prone

even if Doug Fir is tougher, because it is so split-prone

that could make splits more likely

I just want to mention that Douglas fir splits easily! :-)
I'm told that good D Fir is great stuff but I've had boards with 'flaws' where the wood would split easily beside one of the grain lines - a nasty surprise if I'd done much work on that stick.

It is heavy, too.

But people build good skin boat frames with WR cedar, which IMO is less-than-optimum for that role, so probably it's best to just use what you can get easily. Not everybody can access yellow cedar!