I write about photography a lot but I'm also interested in music production. For me an important question is: who will respond best to my posts - my followers or people visiting the related tag? Haven't been able to answer that, as it seems to be a mixed bag.
My photography posts do better than my music posts but is that because of my followers or because music is a much less popular subject on Steemit.
I'd love to see the ability to save our favourite tags. Right now there are people posting in #Photography because it's popular, but they might have huge potential to post about other subjects, if only the other tags got more of a look in.
One thing I do know is that it's actually quite hard to alienate followers. You can go "off-niche" quite a lot without losing followers. Maybe the most important thing is just to do what you love, and what you're good at.