@misterc: I don't wanna disappoint you but with the latest version of custom ringtones the delay is by almost a second and the good thing is that the sound is heard instantly in the moment of the connection. Another thing is that I use mp3 ringtones (my main ringtone is an entire song).
If i uninstall the app the ringtone and the UI are perfect synchronized and are shown instantly in the moment of the connection with no delay!
Another thing: I have pidgin plugin installed but it don't seem to affect the ringtone. To be honest i don't see how could do it!
Good luck!