Looks like i3 is currently 150 members with no staff.
Digging in their wiki, they started with 7 folks and 600 square feet.
To mitigate "sample of one" effect:
Onboarding @ Milwaukee Makerspace (278 members, can't find any info on staff - looks like maybe none)
and Dallas Makerspace's New Member booklet:
DMS_NewMember_Booklet.pdf (1.0 MB)
Results of inquiries RE: demographics are pending