Hi Ian,
You are surely right that a tweet touches more folk at least in the short term. A blog post might have a longer life?

It might also touch deeper as it require a bit more effort on the readers part, hence your thinking here?

Do we think more about a blog post than a tweet? I certainly think more about my own blog posts than I do tweets, one of the reasons I am posting to, liking on and replying to more on twitter via my own site. The effort and friction makes me think a little more.

I am not sure if curation/discussion is more searchable if it is in a blog post than a tweet?

I am barely keeping up with the prep for my wee class, I think a pnd is way beyond me!