They're the only calls I use at the moment...just to be transparent I will tell you that I am on staff for BG...that being said, the reason I looked into being on the pro staff is because I used the double nasty FIRST and liked it so much I wanted to start working with BG. I actually recently got the Canada Hammer 2 myself to replace my old Illusion call...It's much easier to blow for me which is good since I'm much more of a duck hunter than goose hunter. I think it sounds much "goosier" too which a little practice.
The double nasty in my opinion is the perfect duck call...really easy to do a rolling feeder call as well as get up for those loud hail calls...This year I might keep a single reed call on my lanyard as well though for those windy days or if I start hunting bigger waters...but I have called in countless ducks with the double nasty and highly recommend it! Mine's polycarbonate, I can't speak to how the more expensive acrylic since I've never blown or even heard one. (Hence my thread down a couple).