There was indeed a limit of not selecting AP 'Track' plus MFS 'LOC and GP' above 180 KIAS in the Vulcan.
Auto ILS worked OK-ish. But manual trimming and power control was needed and I agree that the hassle wasn't worth it as it didn't give you a lower DH than a manual ILS!
But it gave the GSU trapper something to throw at you on your ICC5 check ride!