Ardan, I think the problem people (including myself) are having is remembering to press the F-Lock key, not thinking that it's some huge out of the way hassle...
Like someone said, it can cause you to lose games. I play alot of Warcraft 3, and the F buttons quick select your heroes...so when one of my heroes is about to die, and I try and quick select them with an F key, if I forgot to press F-lock, that hero is dead, and there's a good chance I'll lose the game because of it.
Perhaps logitech should thinking about releasing some new software that lets you set whether you want it on or off by default...and at least including that software in their next model.
Other than that though Shiva, it really is a great keyboard. Very convenient, I love the mp3 controls on it, and it's also very thing and comfortable, not to mention sleek looking.