How water-resistant is a canon IPF5000 pigment print? Is an IPF5000 print easily damaged by wet hands or a drop of rain?

On gloss, you can run water on an IPF5000 print with minimal effect... as long as you don't rub the print while it's wet. If you rub the print hard while wet, the ink will rub off.

Epson ultrachrome ink is virtually indestructable by water -- you can wet/rub/etc with no effect. While the canon can be damaged with a combination of rubbing and water, I think this is pretty unlikely in the real world. The canon IPF5000 is much more durable than the old HP prints for example that would basically wash off the paper with only a very light rub. (if you pass a cloth over the IPF5000 surface when wet or dab the drop off, it's fine, no problem. It's only if you rub with pressure/abrasion when wet that the ink rubs off.) A wet finger touching a print does not affect the canon ink.

But for outdoor posts for example, you'd want to spray the canon print with clearcoat to be safe.