I can't help you on string choices, but here's some factoids for ya.
-Sound travels at roughly 1,083fps depending on sea level where your at, give or take a few fps.
-Which roughly translates into 700+ miles per hr.
-Deer can react to sound and drop a full body width in 1/3 of a second, slow mo video has proved this.
So armed with those facts, I'd shoot the quieter set up if I were you.
I have personally experienced high hits on deer that tried to duck when shooting bows over the 300fps threshold. Just thought I'd throw that in there for referrence. :rolleyes: