Dave, I've belonged to GWeb for many years, and used photobucket there. I think the only way the pics disappear is if the person who posted the link deletes that photo from their photobucket album, moves it to another album , or otherwise messes with it. Mine have never disappeared.
But the photobucket app for iPad is really hard to use, at least for me.
Another issue with photobucket- I can't upload photos to it using firefox. Works fine with IE. Once they're uploaded firefox works just fine with it/
Karen