About the solar
vents, we had already two models (a nicro first, then an icp), they both unfortunately did not last very long, from 1 year to 1,5 year, before being out of order.
I do not know if we were very unlucky, anyway we tried to have the ICP being repaired, we found out that the parts
were embedded in resin and could not be accessed.
However, we still are going to install a new one, as this the most effective way to remove humidity and odors (it is installed in the toilets) in the whole boat, very silent and works 24 hours a day.
About the "upside down" question, the closing system seems to be as effective and reliable that the one on Lewmar
vents, meaning that there will always be a weak point of course.
We consider it as a very low risk, as we do not plan to sail everyday in the Cap Horn area in winter time....
Hope this will help.