Stainless steel frets is certainly the biggest last innovation, better sustain, glassy bendings, never wear, stay shiny, never rust!
I've put them on all my strats, I mostly play Knopfkerish clean things and they don't change the sound, at least to my ears.
If Tom Anderson, Suhr, Charvel (Guthrie Govan), EVH (Van Halen love them and high en model are ss Frets equiped), Parker, MusicMan (oh man, just try the Cutlass!!) make them, I think that it's not bad for the tone
And frankly, spending $400 for a maple fretboard refret is kind of super yacht maintenance equivalence, regarding the original price of average guitar. Stratocaster $1,200, and 30% additional cost each 5 years!!!
Some guys have made a petition for fender strats = google "Fender, we want stainless steel frets!"