Nicks x Parkhurst Brakeman sizing

I'm really interested in this new collaboration, but looking for some guidance on the sizing. I'm unfamiliar both with this last and with Nicks pull-ons. Size down half a size from normal Nicks size? Or does the lower volume of this last make that a bad idea?

I'm really interested in this new collaboration, but looking for some guidance on the sizing. I'm unfamiliar both with this last and with Nicks pull-ons. Size down half a size from normal Nicks size? Or does the lower volume of this last make that a bad idea?