I have been through 2 plano guide series bags. The zips keep corroding and failing. So have given up on them.
Just yesterday I ordered a custom made bag. I don't know if you have seen the vinyl electricians tool bags; but it is basically one of these made to my sizes to fit plano plastic boxes inside.
The beauty of this is there are no zippers to corrode; instead either industrial Velcro or clips are used. It cost me $210 delivered; these things last for years in a work environment so I am hoping it will last me a lifetime.