KISS. I have a blast force. I will soon get some metal matches. I'll probably replace the tiny one the Boy Scouts sell that used to be on my keychain, merely because it's small, and I can carry it with me everywhere easily. I've used magnesium firestarters, and they are fun, and take a little less tinder gathering skills, and a little more time. It would be better, IMHO, to be able to gather good tinder from around you, but if having the magnesium makes you feel more comfortable in a survival situation, then carry it. And I will continue to carry one of my flutes into the woods as well. And I pray you have more success starting fires with your magnesium than I with my flute...
I've not had much experience with the blast force, and none with the other plastic/metal combos, but I can say, In Alaska, I don't like the idea of mechanical fire starters, especially plastic ones. I've seen knives that have broken under normal use at 40 below, plastic is far worse. Pro's and Con's of my limited use of the Blast Force: I like the little striker, I don't have to dull my own blade, though I get better sparks, marginally, with my blade. I like the storage handle. I dislike the supplied tinder if it does lose some effectiveness outside it's little package. They should give you half a dozen if it does. I dislike the lid on the storage end, it pops off too easy, and the other end, not easy enough...
But it does start fires. A metal match might be more spark for my money, but if I die before I use one of them up, does it make a difference? With my apologies to those on-line I would like to support, I found the blast force here in Fairbanks, and the AAFES sports store can get the metal matches, if I buy them elsewhere, I have to pay postage.
Stryver