Looking it over, Demilich would actually get a pretty decent boost out of retaining her Pleasure Devil-granted at-will Polymorph SLA.  However, even then, all it would do is give her a higher to-hit bonus with her natural touch attacks and SLAs, and she'd still rely mostly on her innate indestructibility and high save DCs when entering combat.<br/><br/>The true utility for it is all the creative roleplaying applications it can be put to. ;D