I think everyone knows my feelings on signing belts.
But some advice: Don't leave the belt in the bag for long periods of time. I have seen tons of Fig Inc belts that get a honeycomb pattern imprinted into the plates because they are rested on the bag for a while. This does not buff out with cleaning.
As for signatures, the ink should be dry by now so they shouldn't smudge unless some type of liquid gets in contact with it.
The new Fig Inc belts come with a piece of thin foam to protect the belts while in the bag.
If your bringing it on a plane, and your paranoid, buy some small bubblewrap at the dollar store, and put a layer in the belt bag as a good insurance policy.