If you come over on a permanent resident visa, that will be alot better (i.e cheaper!!) for all sorts of costs inc. education; benefits (like health insurance, loans, mortgages) etc.
Someone like Alan Collett is more likely to know but I think the temp visa route, like the 457 we came on, is a bit of a swizz and you have to do a repeat performance for the
PR visa(of course, IMHO!!!!); apply for the
PR visa- alot less restrictions/exemptions when you get here. Although it's got the word 'permanent', it
doesn't mean- if you dislike it here- you can't go back!! If I was starting this process now (of course with the benefit of hindsight, I would be more patient on the UK side and get here on a
PR)
If I've understood the visa process stuff (after now having applied for
PR after the 457!!), there's no diff in terms of costs as well for your sponsoring employer either!!! I don't think there's even a process time difference either!! We were led to believe the 457 would be quicker.......some folk have gotten their PRs in just the same time frame; it depends on the, what seem to be yearly, changes in points/protocol/requirements (i.e. the English test!!), the processing and work schedules. Swings and roundabouts.
Good Luck!!