Which Vacuum Cleaner?

Our vacuum cleaner just died on us last weekend, motor burned out. We normally bought cheap ones (~$100) and they tended to last only 3-4 years before they went kaput. We are thinking of getting a better one this time, something that has better suction and lasts longer. Sometime cheap economy is false economy. Having said that I am only prepared to spend up to around $400, so we are not looking at the very high end models.

Reading online, apparently Electrolux, Dyson, Hoover, and Miele are quite highly regarded here in Australia. The two models I am considering in particular are Dyson DC29 Multifloor Radix Cyclone and Miele S5211 Family Caretaker Barrel Vacuum.

Both have very positive reviews from many owners. DC29 is a bagless vacuum with HEPA filter, cheapest I can find is $469 at good guys at the moment, it can come down to under $400 during sales (hhhmm wonder if we can survive with our small handheld vacuum til boxing day?). S5211 is more traditional and uses bag and HEPA filter needs to be purchased separately, but looking at the reviews these miele machines seem very durable and efficient. It's just over $300, plus another $40 for the HEPA filter.

Anyone long time vacuum users have any opinions on bag vs bagless, HEPA filter, and their experience with the different manufacturers? Or anyone know of any good deals going on at the moment?

Or may be we should just get one of those robots one that moves around by itself? That will free some time and Rafa will surely be amazed by it ;). Do they last?

2 dec update: got the miele s5211 for under $300 from good guys in the end. Will worry about hepa filter when it's time to change filter.