But now, I am starting a new job where I'm in more of an admin position (though I still count as faculty), and I'm going to be much more "visible" at my uni and beyond. I thought there could be some value in having an instance here and on birdsite where people who interact with me purely re: that position could just read stuff about my academic life. They don't have to see pictures of my cats or the aphids on my cherry trees, e.g. #digciz
I do follow both of your Mastodon accounts. I don't expect to stop either at this point.
Twitter might be the "better" platform for the professional interactions (because that's currently where the majority of your potential academic contacts probably are).
You can also do much of your longer form work as blog/website pages and use Twitter to provide their links. I see that fairly often.
Should it turn out that Mastodon catches on as an academic platform for the masses, you will have developed skills (as an early adopter) here to prepare you for when they switch.
Twitter adoption by educators was neither quick nor smooth.
Many (most?) are still not "there".