Two icons of bell and "something" seem a little bit confusing to me. I never know what is behind one or another when "ringing". In my eyes it actually doesn't matter what kind of message is about to come. So, I would rather keep just a bell. Could be red colored when it's about user page message or someone mentioning me, and blue colored when it's about a thank or my mentioning of somebody.
One another thing: In the Special:Notifications there could be an option for selecting types of messages to show: user talk notices, mentions of me, mentions by me, thanks ...