I'm planning on purchasing a new mouse, and am currently looking at the Logitech Anywhere Mouse MX ($39.99) and the Logitech Performance Mouse MX ($86.79). Both mice seem great to me, and I don't know which one to purchase. There is a huge price jump between the two, which is something for me to consider. However, if the Performance Mouse MX is that much better than the Anywhere Mouse MX, I will go with that. Is there a big enough difference feature-wise to justify a $50 price increase? If they're relatively the same feature-wise and the Performance Mouse MX isn't much better, I will go with the Anywhere Mouse MX. Which mouse would be better for long-term use everyday in terms of ergonomics, comfort, and overall functionality? Also, are both of these mice compatible with Mac OS X 10.7 Lion? Does anyone here own either of these? Please let me know, and please provide as much feedback as you can so I can make an informed decision on choosing the right mouse for me. Thank you!