Bit late re the mouse use on a mac. But if people do pick up one of the hundreds of quality gaming mice to use alongside their trackpad, you can use Controller Mate (link below) to script up custom button commands like setting your back button to perform the two finger left swipe and restore the buttons purpose. That said a few of the manufacturers are starting to take OS X seriously when writing their drivers now thankfully. http://www.orderedbytes.com/controllermate/
Bit late re the mouse use on a mac. But if people do pick up one of the hundreds of quality gaming mice to use alongside their trackpad, you can use Controller Mate (link below) to script up custom button commands like setting your back button to perform the two finger left swipe and restore the buttons purpose. That said a few of the manufacturers are starting to take OS X seriously when writing their drivers now thankfully.
http://www.orderedbytes.com/controllermate/