I use my nails all the time, and don't tend to have too many problems, aside from the odd mishap unrelated to playing (car door handles and kitchen drawers are often the culprits). Like Mbo, I started as a classical guitarist, and continued using the nails (or the nail/fingertip combined) on steel strings as well. I play medium guage steel strings, both plucking (curling the fingers in) and "brushing" the nail downward. I always found that the brush-on liquid hardeners ultimately created more problems than they solved, so I shy away from them. Three things I do recommend:

1. Constant vigilance: Carry an emery board around with you at all times; reshape your nails frequently (generally using the gentler side, and not digging in too hard) to make sure they don't get too long or irregularly shaped; and get in the habit of running a fingertip along the edge of the nail to check for snags (and taking care of them when you find them). How long is too long varies among individuals, but generally the rule is that you should hold your hand up at eye level, palm towards you, and just barely be able to see the nail peeking over the fingertip. All of this is a pain in the neck, to be sure, and you'll get snide comments occasionally from people who don't think it's macho for a guy to have long nails. But if you want to be able to rely on your nails, this is a must.

2. Pay attention to the angle of attack: Classical guitarists pay a lot of attention to the ergonomics of guitar playing; as a rule, practitioners of most other styles do not. Hand positions, posture, and angle of attack are important considerations in your playing, regardless of style. The striking surface of your nail generally shouldn't be exactly perpendicular to the string, or it will have a tendency to bend straight backwards, gradually weaking it (think of how you bend a paper clip back and forth several times to break it; it's the same principle). A glancing attack generally will sound better, allow for more fluidity in your playing, and preserve your nails.

3. Don't pluck too forcefully: It's tempting for all of us guitar players to hit the instrument hard, because guitar -- particularly fingerpicked guitar -- is a relatively quiet instrument. Avoid the temptation. If you need to increase your volume for ensemble playing, either use fingerpicks (don't like them myself, but it's an option), or amplification.

Sorry for the long-winded response, but I've been maintaining long right-hand nails for playing purposes for over thirty years, and these are the things that work for me. I'm glad you started this thread, and hope these suggestions are helpful.