The problem I can think of is that you only get direct mentions, not replies to your posts (unlike the way it works now). But it's probably not too bad.

true. i wanted to include replies but didn't want to add it as a filter of the public feed because of the inefficiency. an index of messages that link to the user's messages would be doable i think, but more complex to implement.

I wonder if posts should contain an automatic backlink to the user they are replying to? It could kind of be like those dreaded twitter profile tags!

this could be useful for replication (along with adding the sequence number): %Bw6sVzo...