"autistic" vs "artistic" in RP

How well do common variants of Received Pronunciation distinguish between "autistic" versus "artistic"?

Wiktionary gives the distinction that the former uses for the leading syllable the open-mid back rounded vowel whereas the latter uses the open back unrounded vowel,
but it may be hard for many lacking strong familiarity with these designations to imagine just how clear the distinction is for a listener.