see, this is what i dont get... according to Evo magazines tyre test, the worst tyre they tested still has 90% of the wet braking performance of the best tyre - and in the dry, that rises to 91%. in the test they state that like its a really bad thing, but generally i'm happy with 90% of the best available! but specifically looking at pirelli p zeros, a falken FK510 stops better... which is definitely a mid range tyre. kumhos are easily a match for hankooks and falkens, so really dont think they'll be that bad, especially on a car that isnt driven hard. on a car that has sporting credentials that you might actually be driving quickly you might need the extra 10 percent because you're going everywhere 10% faster, but surely a bit of defensive driving, leaving a good sized gap and being aware of other cars on the road will reduce your risk of a collision more than premium tyres.
http://www.evo.co.uk/volkswagen/golf-gti/18309/best-car-tyres-evo-performance-tyre-test/page/0/2
i actually think that where premium tyres are worth more is not in wet or dry braking per se, but that a michelin will still be going after 20,000 miles whereas a cheaper tyre will be worn out in 10,000.