[FeyOberon]

In my opinion as a lady, the length in your pic is completely fine. And when I meet guys with their nails grown out longer on one hand, they get bonus points because I know they play guitar (and do so well enough to bother with that). Of course, that's how I wear mine -- longer on my right hand and cut short for fretting on my left.

You will have to work a little harder to maintain them than an average long-nailed person, due to stress from playing. You can get a formula in a bottle like nail polish, but when applied it soaks in like oil. That will help strengthen them and make them more flexible without you having to wear clear enamel. (I use some stuff from Avon, it comes in a black bottle - can't think of what it's called right now.) Also, invest in a good nail file made out of either that micro file stuff or ceramic; file every time you cut them and they will be less likely to break.

About your picture: in my experience, I have to keep mine about half-again longer than what you have (.75 cm., rather than .5) in order to get a clear sound.

Or, you can get acrylic ones every month like Edgar Cruz (who is a guitar playing badass, by the way), but that could be pretty extreme, i.e., a little strange.