As Carbine added its own roll function there's no need for this addon anymore.
Aaand it's done!
Took your feedback to let the addon follow this rule (i don't care about group size cuz it's too squishy):
If you are not in group/raid -> send roll to /emote (love the standard way to send it as a emote)
If you are in group/raid -> send roll to /party
If you are in group/raid and instance (for LFG-tool etc.) -> send roll to /instance
Nice idea! :)
Until they implement their own, you could do the following:
If the group size > 1 send roll to /party
if the group size == 1 send it to /say