[vel0city]

Aside from the obvious FOSS arguments, what are the big positives to JMAP for me as a user over using a client that supports Exchange?

[Nextgrid]

It's HTTP-based and every request is stateless compared to IMAP, so it should tolerate unreliable connections better. IMAP in contrast is stateful and the process of establishing that state requires more round-trips, so connection establishment is slower.