As a user of gpg I definitely don't think gmail sounds like a good idea and given my not-very-broad band connection I suspect the performance would be awful. Telling google my private key and pass phrase would be a really bad idea.
I currently use thunderbird, with the enigmail plugin, and can't find huge amounts missing modulo some difficulties using the search to find that email I received some time ago.
I don't use twitter and sites like FB, linked-in, etc ask for personal information I don't want to share. IMHO just not putting that information on the internet is far more secure than using FB privacy settings. Is this approach just out of date?
I also don't feel the need for what RSS provides. I am aware that some streams of updates which might cost you money are atom feeds.