Roland Ivory feel keyboard roughens due to finger nail scratches. How much and how fast depends on your playing style and how much you use the keyboard. At first it is very subtle and only on key you use the most (mid keyboard).
My RD700GX with Ivory feel started to show the first signs of wear after a few weeks. At first I though it was some skin grease and tried to clean it. The dealer was at no help at all. Luckily I found some info on the internet (more on that later). Roland confirmed the issue and replaced the whole keyboard with a new revision (revision february 2009). Unfortunately the new keyboard suffers the same problem.
Roland support is very helpfull and commited to solve this issue. But knowing that this issue is known to Roland for quite some time I decided not to wait for the final solution and returned the keyboard for a refund.
I know from Roland support that this is a general issue with all Ivory Feel keyboards (not limited to the RD). To put it in perspective, only a small part of ivory feel owners notice or feel the wear because it is subtle. Some other people that played my RD only noticed it after I mentioned it. So I'm one of the few that is bothered by this. Also I took in account that the roughening is progressively getting worse.
Take a look at some
photo's
Other sites:
http://www.max.grenkowitz.net
http://www.pianoworld.com
http://www.fastonkeys.com
http://acapella.harmony-central.com
or Google for 'roland ivory key wear'