Having the glass removed is a huge plus although I know that's not always possible. I can only remember having one framed item with glass shipped to me and it arrived with broken glass shaking around inside the package. At that point when you can hear broken glass bouncing around inside keep your fingers crossed that the sharp glass pieces didn't damage the print or painting.
I lucked out with no print damage
I've heard of people applying tape (maybe masking tape)? over the entire glass portion of a framed piece. Therefore if the glass breaks during shipment it will remain in place and lessen the chance of glass damage to print. I could only imagine the stickiness and headache associated with trying to remove the remaining tape residue!
