No, there is not a compelling case - we should merge the chats into a single room.
A second room for topic-based discussion does make a lot of sense - it stops the general banter from the main room treading all over the more focused chat. But we simply don't have the chat volumes at present to make this a serious problem.
Separation just gives us two sparse chats. @JanMurphy's sterling work on the weekly chats often spends a week just echoing in the Conference, while Roots has been suspended for inactivity a couple of times this year. Although the Conference has more messages overall than Roots, it has half the number of all-time users (20 vs 40) which suggests that fewer people are even seeing the content there. That really doesn't help.
(If those numbers are correct, given the site stat of 4135 "users", only ~1% have actually typed anything into Roots at all, and 0.5% in the Conference!)
I don't believe we're actually realising any benefit from having two rooms, so I think we should consolidate chat to a single room. It's presumably not too hard to split out again if the omnichat becomes congested, anyway.