i havent yet used it on my harmony, but i had a similar issue on a few other products, and after trying everything, i found out what seems to have the best feel plus doesnt look like ass.
its a spray rubber coating.
[Link: yachtsofstuff.com]
it gives things a kinda semi matte finish, but feels really good, after time it will wear off, but just respray it... obviously you will need to take the remote apart before doing it.