The kenmore is cheaply made
The Kenmore is not half as good as the Panasonic, The Kenmore is cheaply made I checked them out . Do not forget Sears gives Panasonic a target price and Panasonic builds to that target price and cost factor. When Panasonic builds their own top of the line vacuum they build to make the best vacuum they know how.
I am also not a fan of the Kenmore brush roll, not Agressive enough and $130 to replace. The Miele tools are better but it does you little good when the bag door is broken or the hose is bad and so on. The S7 is not built to the same standards as the Miele canister line.
Consumer Reports test something for a couple days and cost is their main driver in recommendations.