For the record, there are no bad feelings on the Matrix side towards IRCv3 at all. The protocols are very different, and the design & architecture decisions in IRCv3 look fundamentally different to Matrix. In the end, Matrix is trying to be an openly federated object database with pubsub semantics - a standards-based decentralised encrypted Firebase, if you will. I really don't think that collides with IRCv3's aspirations, and we're looking forward to updating https://github.com/matrix-org/matrix-appservice-irc with IRCv3 features as they land. We're also looking forward to IRCv3 stuff to add to https://github.com/matrix-org/matrix-ircd, which is a Rust server which exposes an IRC listener for the entirety of Matrix. The open communications space has enough threat from silos like Slack and WhatsApp without in-fighting, and I'd hope the communities can get along and support each other rather than the opposite.
In terms of the line protocol - we all agree that HTTP+JSON is an inefficient baseline for Matrix. It's just a matter of time for someone to propose a proper binary transport (although HTTP2+gzipped JSON really isn't that bad, and works fine on dialup speeds). Luckily this thread has prompted a few people to offer to contribute one though, so perhaps we'll see some progress there at last :)
In terms of the line protocol - we all agree that HTTP+JSON is an inefficient baseline for Matrix. It's just a matter of time for someone to propose a proper binary transport (although HTTP2+gzipped JSON really isn't that bad, and works fine on dialup speeds). Luckily this thread has prompted a few people to offer to contribute one though, so perhaps we'll see some progress there at last :)