> Is it that the possibility of being let go after a large project that you performed a relatively specialized role on feels just about right for a consultancy, but not for a business that carries themselves like a long term player?

This. Someone there could hire me onto a project that fails for some reason out of my control, and then, because I’m older, I wouldn’t get picked up by another team.

I don’t know if project-pickup retention is still how they operate; it’s several-year-old anecdotal information from a past worker there before they were acquired by IBM.