[prodigal_erik]

If you have multiple streams, you can give lower latency or better durability to critical or low-volume messages.

[encoderer]

This should definitely take place at the aggregation level. There are great tools for this already. This is definitely an implementation detail we developers should delegate to the systems guys.

Not to mention, it's just less development work to send out messages with, say, different syslog levels and be done with it.

[imbriaco]

You can do the same thing with the local or aggregation tier syslog daemon if desired.