The KSC-75's bendable wire clips alone make it head and shoulders above the KSC-35's unbendable plastic clips, which were not designed to get the drivers in the proper position on my ears for me to hear them as they ought to be heard. As a result the 35's always sounded to warm to me.
Once I got the 75's and played around with their orientation over my ear, I was able to get them in a sweet spot and hear the best out of them. For unamped listening I feel they are unbeatable in terms of sound, price and convenience. Though the Grado SR-225's do beat them in terms of sound, it is not by nearly as wide a margin as their price would indicate, and the 75's are more comfortable and portable to boot. And when amped, the differences shrink even more.
The only aspect where the 75's are always beaten is in terms of soundstage and overall coherence, which they are not very good at. The soundstage sounds artifical and you feel as if though you are listening to two speakers, rather than a single, unifed soundfield.
But, I don't use the 75's for my critical listening. They are fun phones and have an unshakeable place in my coterie of headphones.