It's actually pretty amazing how much difference a few drops of lube can make.
My rk-9000 at home got the lube treatment and it feels solid as a rock. Completely tight and well built. The one at work seems to get more and more loose and rattley. I'll have lube it soon because it hardly seems like the same keyboard at all.
If you want your board to be at its best get some plastic friendly grease (lithium, silicon, di-electric) and lube the stabilized keys.
I thought I'd mention that wasdkeyboards lubes their keys for you.