I don't like the S7, much prefer my Felix in more or less everyway. One thing I will say is the quality of Miele bags are very good, although the self closing flap never works as dirt accumulates around the neck of the bag rendering that flap useless, and the newer type sebo bags are just as good quality.
I would say the DC41 MK2 grooms the piles and has stronger suction than the S7 despite what people are going to tell you. As well as that, Sebo and Dyson give you 5 year guarantees, and the dyson one especially is excellent, they wont try and wiggle out of anything, they genuinely want you to be happy with the product. As you may know, their policy is if they cant repair the vacuum with the tools in their van, they give you a new machine. I cant vouch for Mieles warranty however, but I doubt they are as good as that.