If the mechanics is the same as a knife blade the radiused edge carries more strength at the nose, as the head’s width is carried forward a bit more. In practice most heads of the Zwickey style (Zwickey, Magnus, Stos, etc.) have a tripled nose which gives way more strength than the radius alone. Then you look at other successful designs like the Hill and Simmons that have a negative radius. There is likely a practical trade-off between penetration, cutting, ease of manufacture and plain ‘ol “this looks good”. There is no question that the Eclipse and Journeyman broadheads just plain look good.
I like the straight edges for the ease of setting the initial angles on a S-24 Tru-Angle jig with files. And thereafter it’s easy to “field sharpen” a used head with a file I keep on my quiver. You can also hone a straight edge without the need to rotate the head as it is drawn along the stone. I find the Stos to be “self-jigging” if I lay them on a dummy credit card (the banks send me these regularly).
I’ve got a modest collection of glue-on heads and it’s a good mental exercise to look through them and wonder “why was this designed so?”
Unfortunately, the answer in many cases seems to give a nod to the old bass lure philosophy: a lure that sells well is more often designed to catch fishermen, not fish.
