So I took my 8 year old HD595s, that I've used every single day since I got them, and sent them off for the flat-fee Sennheiser repair service when one of the arms holding an earpiece broke. These headphones were shot. They still sounded great, but the pads and headband and every part on them was worn out -- to the point the earpieces could just slide off the end of the headband. Can't really complain. I used them literally every day (don't even have speakers hooked up my my computer) for 8 years. I figured that for $79.95, the worst case was probably refurbed HD595's, but I suspected there was good shot at getting HD598s back as the current model replacement.
So, I paid the $79.95 (that included UPS shipping labels both directions) and sent them off last Thursday. They arrived at Senn on Friday. Replacement was shipped on Monday and arrived today (Tuesday). Refurb HD598. Looked perfect, just packed in a refurb bag instead of a retail box. So, for $80 and my busted up 8 year old totally worn out 595s, I got a set of 598s. Not a bad deal at all.
I'll do that deal again when I've used the 598s for eight years!
The flat rate repair/replace service isn't much of a deal on some models, but on others, it's a fantastic deal.