As I know, players use a mix of IMs,
heRO facebook group, and ye olde shouting on @Main to chat. Some use both, some neither. I log FB once a year or less. One chatroom is a nice idea, though I don't know if everyone will adopt it over existing tools we had.
For me, I'm always curious about IRC, (blemishes my nerdy resumé) would be good time to finally learn. Sure sounds great for a budding RP party, and any social-minded players. I'd use one, yupp.
Ps. to combat loot messages, switch to Combat Log. This one we can configure what we want it to show. Click the "+" icon and enjoy a cleaner chat world. *-*