If you haven't packed it like you expect a gorilla to handle it, you haven't packed it well enough.
FedEx and UPS are more likely to damage something than Greyhound simply based on how much and how they handle it.
with Greyhound, your item gets lifted two feet off the ground and put on the ground several times (depends on how many busses it has to take). It never goes to a distribution center or sorting center to get touched, moved around, and reloaded.
Greyhound doesn't deliver. They only remove your package off the bus where it waits at the station for you to come get it. There's no risk of damage from the delivery person tossing it off of or on the delivery truck.
I've had good experiences with greyhound, UPS, and FedEx. Greyhound has never damaged an instrument for me. The same is not true for the others.
I'd have to say that bloke and Tubatinker have probably shipped more stuff on greyhound in the past couple months than I have every shipped or received in my whole life, so their experiences count more than everyone elses.
