I had problems with a BOA fitting which seized after a long wet Audax. I have narrow feet, which seems to be the opposite of nearly everyone on this forum, in the UK, so the brands I like probably won't help. What I do as a routine on events of 300km or more, is take my shoes off when I get to a control and allow the feet to breathe.
The other thing that makes a difference for me is socks. I use Bridgedale inner walking socks for hot days, which again help with the feet breathing. On long events where its going to be wet, I tend to carry a spare pair of socks so that I can have dry feet at least briefly.