[mastazi]

> This message I will reply to if/when I'm around.

which is perfect because the precondition is that the other person wanted to know if/when you're around

> "Hi" could be I have a quick two second thing, or I'm about to dump 6 pages on you

so you agree that "Hi" carries zero information and should be avoided?

[Volundr]

Yes exactly. I'm agreeing that this is the right alternative and will get a response from me much faster than the empty "Hi". "Hi" <brief description of why I'm reaching out> is always superior.