To hide or not to hide (symbols)

Been a long time since we discussed gcc hidden visibility for symbols. Last I remember, this was supported in (T)Qt3, arts, tdelibs, and tdebase. I tried building my normal package suite with this option enabled in every package. Some packages built but ignored the configure option. Some failed to build. Some built and there were no messages at all about the option. Removing the option from the failure group allowed the packages to build. For the latter group, as no errors or build failures occurred, I presume the option is supported. Still, is this a good idea? I read a bit about the topic and the information is way over my head. The only thing I do understand is using the option is supposed to reduce libary size and improve loading speeds. Darrell