If you backpack, there is a good chance you carry something to make a fire. If you are responsible, you likely have some redundancy being that the ability to make fire may be the difference between life or death, or more likely, a tasty marshmallow or warm meal. Redundancy in fire tools usually includes matches, a lighter, fire plug, or some kind of flint.
Like many backpackers, I generally carry a necklace with a few things on it. Whether as a last ditch effort for safety or peace of mind if I ever get separated from my backpack, it's something I always have. On it is a flint striker, whistle, and microlight. On the whistle, I glued a button compass which has probably been more useful then anything else when I need a quick direction reference. I've gone back and forth with whether to include my Swiss Army Knife mini as it is a bit cumbersome to have all this stuff around my neck even though I find it to be very useful and far more available if not otherwise stuffed in a pocket or sack.
About a month ago I was studying my necklace for wear and noticed that my flint was pretty worn both from use and likely from my body sweat. I also noticed the molded handle was cracked. As I tinkered with it to see how bad it was cracked, it came completely apart. I think it's fair to say that holding more on the flint than the handle in the future will probably be a smart choice.
With that, I needed a new flint and decided to look for another Swedish FireSteel to replace the one that I had just broken. To my surprise, there was a new FireSteel on the market listed as a "2.0". It was a little bulkier than my previous FireSteel. The striker was shorter in length, but was incorporated into a whistle. The molded grips on both were much thicker than previous versions, possibly because others had the same problem I did.
The whistle I carry is an ACR because it was dubbed one of the loudest pealess whistles by the Coast Guard. Oddly enough, and having used it several times to get the attention of friends or scare off an unfriendly bear, I really don't find it to be that loud. In fact, the pitch itself is more annoying than anything and the sound really doesn't travel that well. I do like the fact that it doesn't require a ton of effort to blow, as it seems air seems to be better controlled. For many years before college, I refereed youth basketball. Any time I blow my ACR, I wish I had my old referee whistle which was easily capable of deafening anyone within the building. With a pea though, it is susceptible to freezing, so I leave it at home. I think the whistle most similar to my old referee whistle is the Fox 40 as it seems to have a rolling sound, although it exhausts air pretty quickly. Comparing the ACR whistle to the new FireSteel 2.0, they really aren't that similar as the FireSteel 2.0 sounds doesn't really generate a loud enough sound to be useful. The ACR is a little easier to blow because of the way the FireSteel 2.0 tried to incorporate it into a handle with a lanyard punch right next to the whistle part which gets in the way a bit.
Regardless, it's always nice to carry gear which is multifunction and the FireSteel 2.0 (http://www.light-my-fire.com/) may be perfect for your needs. As for me, I'll stick with the better whistle (either ACR or Fox 40 depending on my whim) and I'm debating on whether to carry the more robust flint stick.
UPDATE: One of our fine readers suggested the Exotac Nano Fire Starter (http://www.exotac.com) which is a lightweight and waterproof solution to fire rods otherwise damaged by sweat and moisture. I've got one on the way. They are a little more expensive, but it's nice to still be able to carry it around my neck and know that it isn't going to get damaged.