I have the FOX40 and I am noticing a lot of redundancy on this site. Is it a good idea to have redundant whistles?
If you mean redundancy as in multiple whistles, yes, that's a good idea. On my hiking backpacks I attached a whistle on each of the main zippers. Why not? It is light, inexpensive and serves a practical purpose.
If you want inexpensive redundancy, then I recommend these fake Fox 40 whistles that are just as loud as the real thing:
http://www.amazon.com/Price-10-Pieces-Pe...4448&sr=8-2(Do an Internet to find an even lower price elsewhere.)