Ive just done peno tests using several styles of 2 bladers..these are my findings..
The single bevel 2 bladers get much more peno that double bevels..esp the headfs with the more slender taper.
I even single beveled what is normaly a double bevel design,and despite loosing a little weight,it still out performed its double bevel twin.
The single bevels hold their edge far better and last much longer..But ive known that for years from experience using both.
So I know what ill be using this year..and thats all that matters..lol