Hey Dbar71,
There really is no problem with changing the surface on Ogre Particle, and as long as it's not polished, you should not lose the shadow effect. The particles on this ball are derived from a soft, pliable material, and does expand with oil. This is intentional, and helps get additional traction on the lane.
That being said, you can polish the ball if you would like. It will not hurt the ball, but bringing it back to box condition will require a little more effort, because you will have to use a coarse grit paper in order to get to a fresh surface. Typically, hitting it with 320 sandpaper, and then bringing it back up works just fine.
Like the Granite, the surface does attract some dirt, but it isn't as noticeable or as much of an issue with the Ogre because of the color. Simply do some occasional cleaning/resurfacing, and you should have a ball that lasts for a long time.
Jason