I just bought a bagless Dyson V8. Never thought I'd touch a Dyson. But it's not bad. Easy to use and love no cord. The carpet hardwood floor brushes are perfectly sized to fit places many other vacuums won't. Not sure what all the complaining about dust flying around during the dump. It's quite easy to do without making a mess. Maybe it's not worth the $600 I paid for it for most people, but there will be sales and price reductions to be had for the patient.
A good vacuum is the one that gets used, and so far, this one is getting lots of use. And no stinky bag. Can't say that for any other bagged vacuum I've ever used. Sooner or later, they all stink. And yes, I clean them.
As for Miele, I find there bagged canisters (I've had 2) to be very well designed, top quality and more quiet than any other canister I've ever used. Hope their bagless has similar quality and they can give smug Mr. Dyson some competition.