I could be wrong but I think the issue is that I'd be bridging Matrix to my Slack organization, which I would be downgrading to 'Free', and so any communication

I could be wrong but I think the issue is that I'd be bridging Matrix to my Slack organization, which I would be downgrading to 'Free', and so any communication that happens with external people via the Slack/Matrix bridge will be doing so via the crippled 'Free' account. As it pertains to inter-company communication, 'Pro' allows for channels and group chats, whereas 'Free' only allows one-on-one communication. So, again I could be misunderstanding, but I don't think much is really gained here, relative to (say) implementing Matrix for internal use and also asking employees to keep Slack running for certain external chats.