I have a very good experience with Dekoni and Brainwavz ear pads on closed/semi open Beyerdynamic and Fostex headphones - those are less prone to drastic acoustic changes due to ear pad swapping (as long as ear pads share similar properties with stock ones).
I replaced HD560s ear pads due to comfort issues, so buying another pair from Sennheiser would not really achieve my goal.
Btw. Dekoni for example publishes measurements of their + stock earpads, so one can use these charts as a guide for additional EQ tuning if necessary.
Anyway, I believe that most folks are happy with these headphones as they are, I am just not one of them and I wanted to support the other unfortunate member who complained about lack of comfort..