I would include her if she already didn't do work with a plethora of other circles already. miko and monotone are more of what come to mind, being vocalists who do a decent amount of work for IOSYS but have their own circles.
uno's the only one to actually come from his own circle, Sapporo Hardcore Channel, OTAKU-ELITE Recordings was formed after D.watt's involvement with IOSYS (their Ablitrosicks still has IOSYS' "IO" catalog stem for reference), and I've never seen minami or void outside of IOSYS works.
On topic: I'll just leave
Foughten Field here.