I think the real problem with this model is the probable lack of QA for long interval updates.
I ran into this with Gentoo all the time. If you update your Gentoo system every week you are good to go.
If, however, you wait a couple of months or more between updates something is almost certain to go wrong because the developers never considered data or configuration file conversion from version N-2 to version N, only N-1 to N.
Ubuntu *already* has this problem to some degree when you try to update from version 10 to 12.