I was able to draw last year in a blind, but the bird was clearly a hen... so I let down. She was about 10 ft from me and never saw me draw. I think blinds work, but you HAVE GOT TO also assume they can see you in them and wait until they are turned, head down, looking away, or concentrating on a decoy before you can draw. I think it is also good to be able to hold your draw for a few secs incase you need the time for the bird to not be looking before release.
Best of luck! And check out "Turkeys 101" its thread I started to discuss this same thing about a month ago... great advice on there : )