I don't believe that there is any problem putting the pads on, the breakages happen when trying to take the pads off.
And as I see it there is no reason or obligation why they should give free pads to existing customers, there is nothing wrong with the stock ones on the phones.
In my experience* the pads came off okay. Just slide away from one of the tabs as much you can and gently pry, repeat for an adjacent one and last two can slide right out. The problem is it can be very hard to put them back safely where you *need* to bend the fragile plastic to get it in place. I have one broken tab and one extremely worn tab on one of my ear pads now, and luckily got the other one on cleanly.
It's hard to say Fang
owes upgrades to existing customers, I was just saying it would be extremely nice of him if he did.
To everyone suggesting we have no reason to take the earpads off, there is someone who just posted here** that he found he was missing the proper damping material on one earphone after taking the pads off. Maybe we want to double check the work... or maybe we've just worn out the pad and need to try to apply a new one. If they're built to be user replaceable (they are, there's a spare in every box!) then they shouldn't be that fragile and *have* to be bent so severely to fit into place. Even the KSC75 are easier to safely replace, and they're foam stretched over spikes!
Anyhow, the point of my post was just that if the new leather pads fit on in the same way, I'm not going to risk buying them when I know I have a good chance of breaking them just by trying to install them. On the other hand if their tabs are made of a new material or somehow function in a different way I think I
have to since my right pad keeps sliding off now and especially because the earcup's yoke presses up against, and pry off, the weakened pads when it pivots.
* limited, not trying that again!
**
http://www.head-fi.org/forum/thread/493214/hifiman-he-6-planar-magnetic-headphone/3885#post_7548555