Ever since Autobuff was broken by Blizzard several patches ago, I've been looking for something that can get a clear reminder off to me while in combat that battle shout has faded. Maybe a warning in the /rw frame and/or something to the default chat frame that would have its own unique sound event.
Those do not have a custom sound connected to it, nor do they put a message in your chat window. I am looking for something that is very easy to catch/hear while in the middle of PvP and PvE combat. I have the latest SCT and do not find that it can provide this type of warning.
Buff Reminder on Curse used to work good for this, however, the mod cannot be configured. The message stays in the middle of your screen for up to 30 seconds after recasting.
SCT supports sounds using a custom event. Just create an event for BS fading with a sound of your choice and add the aura fade msg event. See sct_event_config.lua for more details.
I actually handle BS using macros. I have it tied to execute, bt/ms, and hs so that if I don't have BS up when I perform one of those, it casts BS first instead. I can post the macro if you are interested.
EBR has been updated so that it now stops displaying the warning as soon as you reapply battle shout, though doesn't play a sound and obviously an Ace2 addon would be preferable, but this works for me in the meanwhile.