I've heard the arguments before regarding spinning down drives, and I'm still undecided. So I thought I'd ask your opinions about this topic, and after I weigh everything out, I'm guessing I'll still be undecided. 
In regards to this program http://macintoshgarden.org/apps/sleeper please state your case Pro or Con for spinning down drives. I think it's a given that this program is terrific for an energy star CRT so we'll move on from static devices to that of dynamic.
On the Pro side, as far as I can tell, spinning down the drives ...
- saves energy (and therefore costs)
- helps to reduce heat buildup (of course heat is detrimental to your CPU etc)
- helps to keep noisy drives like the older 7200 RPM Barracuda's from continually assaulting your hearing (I've actually done extensive sound abatement in a rattling 7100 case and this really isn't a problem any more).
- possibly reduces wear and tear on the drive's motor, but this is the most controversial aspect of continually spinning down and back up.
In the Con camp, there's...
- the wait time while your drive spins up (a matter of 20 seconds or less really)
- the possible increase in wear in your drive's motor from continually spinning down and back up.
Considering everything, there appears to be a good compromise for spinning down, as long as it's not done excessively. Perhaps spinning down after 30 minutes of inactivity is a good compromise.
Of course there's the camp that believes that never spinning down is the way to go, if you want to save wear and tear on your drives.
Thoughts, Pro/Con? Have I failed to mention anything to consider?
