Campanula advice, please

Hi - I need to plant some ground cover which will fill in some serious bare patches (waiting for shrubs to fill out!) in sun and part shade, south and west facing, neutral soil - and I'm wondering if there's much difference between Campanula Portenschlagiana and Campanula Poscharskyana - I already have Portenschlagiana growing happily in contained beds but I don't know if it would turn into a thug in open ground!    Site and soil are perfect for either, but I want something that isn't suckering and won't be a nightmare to dispose of if I ever change my mind  Thanks