WHat's the scroll wheel like on the MX Rev? I had to replace my MX1000 a few months back and went with an MS Laser 5000 which is OK, battery life is far better than the MX1000 but the scroll wheel is really annoying because it's just smooth so flipping between photos in Lightroom or AcdSee is nigh on impossible. Hence I'm after a new wireless mouse with an old fashioned bumpy scroll wheel.