You ridden both?
I've never been on a Blackfish (or handled one). I understood Pono's comment was due to the Blackfish very parallel outline that it's not so turny on a DW. Which is same same feeling I get on a Naish Maliko which has awesome stability for it's width and is a great allround board but is more of pivot off the tail kind of turner on DWs rather than carving up killer turns.
So what are the differences in rocker and rails? And difference in ride if you know both?
I haven't ridden the Maliko but I've handled it thoroughly. I believe Pono's
Blackfish is a 2015. The 2017 is quite different. Less nose rocker different bottom. Dave added some rounded section in the front with more rounded
rails which become much sharper beyond the rounded section.
The Maliko has more rounded rails, especially in the front section.
as for the the rocker, here is an image to show the differences.
I didn't have much issues with turning my Blackfish. My fin position is
16" from the tail and with the right fin I never noticed an issue, but then
again, I don't have much experience downwinding in conditions like Pono's
or at all for that matter so I can't really compare.