OK can confirm that.......
3, Vodafone & Optus sims will work on the mini 9 - the Optus sim needs a change in the configuration to work (have forgotten change and will post back an edit). 3 works by default - Optus & 3 run using dell 5530 & dell wireless controller.
Vodafone has been causing me some recent issues with the dell wireless controller have gone back to using the Vodafone software. Dell wireless controller was working perfectly well until recently it stopped working correctly. Vodafone must have changed a setting somewhere but I'm unsure what it was.
Only sim not tested is telstra - wife has a wireless version so will test this soon.