I shot primarily 3-blades for years, heck I still do... But, I bought an EFA quiver and just have a hard time getting my "goto" 160 Snuffer into there! I shot 2 blades last year, basically for the quiver issue, and for what I've read on here about their ability to take down game.
Well, I took four shots at big game animals last year, and three animals on the ground with a total of 105 yards of tracking. And, two of the arrows went through one doe (spine, and a follow up lung shot). And when I say through, I mean through into the dirt. That is effective in my book. Plus my Magnus 1's were very easily sharpened. I'm a fan via convenience and from experience.
Now, the 2-blades I like are WIDE 2-blades (1.5" or greater). Magnus 1's, Pearson Deadheads (wide, 1 5/8"), or Silver Flame XL @ 1.5" and my favorite the Silver Flame DS @ 1 7/8". Plus I don't want to get into the Single bevel vs. double as all I've shot at game are double.
Knock them if you want, but they work, period.