I'm not sure if the new version of BYOND just doesn't send a message at all, or if people are just too stupid to see it, but every day I get people whining at me that they cant connect to my games hosted on 430. They say it just says connection failed when they try to login, and updating their BYOND fixes the problem... so iuno <.<
I actually came across this myself (having dial-up means you don't update with every release). The splash screen will give a 'connection failed' message, but the 'out of date' message is only shown in the Options and Messages window, which most people never even see anymore.