I have a Santos Hermanos guitar that I have had since about 1973. I was living in PNG at the time (Tropics), and one day in about 1977 there was a loud bang and the bridge came off, unfortunately in pieces.

I made enquiries with a guitar maker in Melbourne at the time, and he offered the opinion that hide glue can be attacked by micro-organisms (mould etc), and recommended a synthetic glue.

In the event I glued the new bridge on with PVA glue, and it is still there after 23 years. Apparently the water-soluble nature of PVA is not particularly important in the tropics, but resistance to mould is.

Mind you, I appreciated the hide glue when I had to repair the guitar a couple of years later (replaced back), as it was a breeze to pull it apart.

Regards
Chris