as yuheng said, no special care is required and there are no mods as of now. just get the right fit with the tips and treat it as gentle as your GF - u should be fine (however SM freaks mite find they need to buy a new set once a month or so ). sides the mylars comes with replacement warranty.

IMO, unamped the M2 will be on the warm side while the M3 is better balanced across the frequency range.

I dont believe PK series will provide any isolation whatsoever and IMO both the Mylars and PKs are equal in comfort.
FWIW my uber portable rig is 1st gen shuffle paired with a M3. though it cannot compete with my regular porty rig, i can honestly say that the sounds emanating from the shuffle > M3 satisfies adequately to the point i dont feel im missing lots. to qualify the above statement, let me state that i can no longer listen to CX300s, any sony or philips earbuds or blasphemy of all blasphemies...any original included earfons! .

bottomline IMO the M2 pairs well wit an uneq'd shuffle