I just got a used turbomolecular pump and now I'm looking at step down fittings. Are there any strong opinions about this type of extreme reducer? A conical reducer would have more natural flow characteristics, by unambiguously sending molecules into the entire diameter of the blades, but they are more expensive. But, maybe it doesn't really matter much in practice? Ultimately it looks like a lot of us are stepping down to 1/4" and 1/2" piping anyway...
I'll be monitoring/controlling the turbopump with a raspberry pi, which is a fun project.