i think maybe the clue is in the op "conversion course"? these can vary in quality quite enormously, from pretty wide in content yet shallow, to very narrow yet deep in structure. and i'd tend to agree, people who have one of these would not match up to a decent graduate in the subject.
however, no conversion msc course in computing can match a specialised msc course which has, as an entry requirement, a reasonable first degree in computing. these, whether by research or taught, can be pretty involved and committing. i'd always give credit to anyone who possessed one of these, regardless of industrial experience. but just how you'd weigh up a 'good' msc against industrial experience, should i think be taken on a case by case basis.
having experience as well as a good msc, is of course, the best of both worlds. but then again, for changing tapes, who needs either???