The only thing that went thus far were the leather cups (twice) that are fortunately easily replaced. OEM are $$$, while after market alternatives I found to be just as good and are only $.
My battery is still strong. Probably around 10-12 hours of use.
I have the same experience on the battery: my pair is almost 3 years old and I can go about 2 days of work (~12 hours) before I have to charge them.
The analysis in the page discussed in this thread doesn't match what you're saying: knockoff cups are inferior and degrade noise cancellation.
But you paid 300-400$ for headphones, to me it's worth paying the OEM premium just to make sure they keep delivering the quality and experience I was looking for initially when I paid the high price. Otherwise, you might as well buy the lowest priced noise canceling headphones: you'll get a commensurate experience but you won't break the bank.
Anyway, to each their own :)
The problem is aftermarket cushions may not do as good of a job at passive noise reduction.
Follow the link and check if you have the right number of clips on your aftermarket cushion. Obviously this isn't the full picture but is certainly a large piece of it.
And I am the guy who spent 4 times a few hundred on AKG studio headphones but replaced the ear cups with some much, much cheaper but better feeling ones.
To each their own :)
Mum bought new last year because pads were worn, I got her old set - uses a single AAA battery and lasts across the globe and back (~30 hours). Unfortunately she didn't like the new rechargable set, and neither do I..