I've had about ten FW's and never had an issue with fins boxes(FSC or Futures) or dings that suck water.

I did snap one (FST) clean in half though and left it in an Indo village years ago, i was back there in May and kids were playing on it everyday in the lagoon sometimes for hours..

I checked it out and gave it a paddle, expecting it to be waterlogged and mushy and wet, but the strange thing was it wasn't, it didn't feel heavier and was still as buoyant as the day i snapped it maybe it had sucked water but it wasn't visible or obvious, not even mouldy????

The balsa rails though, different story they had sucked in water a few inches in and gone mushy and mouldy.

Even when it had been sitting around for a few hours it was hard to tell if it had sucked water, nothing obvious when you tried to squeeze the EPS where it was snapped..

I did read in swayback thread that EPS tends to suck water when it's a ding in a board (like a vacuum effect) but not so much when it's fully exposed?