Ha, yeah, there are some use-cases where OTR will work better than OMEMO: for example gateways to other systems. Because OTR uses normal messages they survive even when changing the messaging protocol. I’ve seen people back then OTR others from XMPP to Facebook.
OMEMO is basically Signal in XMPP-clothing.
From what I can see CoyIM is a proof of concept XMPP client that supports new OTR standard (OTRv4?): https://github.com/coyim/coyim#getting-started
But besides that everything supports mainly OMEMO so having an OTR-only client would basically mean talking only to oneself :) (this has some benefits though ;) ).
Ok, forward secrecy is a problem in itself as it denies availability, which is important in some use cases such as where traceability is required or simple archival.
And as has been pointed out, it didn't play nice with carbons. This latter point could no doubt have been addressed in a revision.
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