Since new client is getting some pre alpha testing i have an idea to add to it.
On the patcher screen add a simple ping test to game server running 2-3 tests and displaying some info depending on it.
"ping optimal, nothing can stop you"
"ping average, have fun"
"ping bad, you may have problems playing league and/or experience disconnects from game. Do you accept that and still want to log in? YES/NO"
This way when someone's connection to game is bad he can choose to try some other time or play knowing about possibility of lag.