When I began my novel, it began as a novella. I missed the shorter F/SF works of my youth. I have increasingly come to the conclusion that the industry's over-concentration on long works is bad for the genre. (Mind you, I'm not poo-pooing the long works. What I'm poo-pooing is the industry's myopic attention to those works.) To no small extend, that limited the professional viability of the endeavor, so I cast off any idea of this being anything but self-published.
I have come to recognize two important things about myself since I began the latest work: 1) I am happy writing, but I am not happy writing all day long, and 2) I don't think that I will ever be fast enough for a book contract.
As for independent publishing (or vanity press, if you like), I am well aware that print runs of 100 are "normal." There's a few success stories out there, but they are few and far between.
I am also aware that independent publishing is the kiss of death vis-a-vis commercial publishing. No matter how professional you are, independent publishing puts the mark of Cain up you as forever unprofessional for the rest of your life (unless you prove that you can make money).
For now, I'm still not committed to any plan. I'm exploring Amazon books on demand and Lulu. But first, I need a manuscript that I am happy with.