V1, Vr and V2 were developed as part of the certification basis for civil transport category aircraft. The main factors behind this triad were accelerate/stop distance and some guarantee of a reasonable climb gradient with one engine failing at or after V1.
The Canso/Catalina is a military aircraft. While quite capable, anybody who imagines that its engine out climb gradient meets civil transport certification criteria needs to have another look at the paperwork.
As far as I'm concerned, not quite enough runway/stopway to complete a reject is not nearly as bad as finding out in the air that you can't make it back to the runway.