Logitech G600 - any other similar mouse?

toshibitsu

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I've been using the G600 for awhile now as I like the size(width) of the mouse. Most importantly, I love the "back/forth(left/right)" function of the middle mouse button. I don't play MMO's/RPG's so do not care about all the side buttons.

Is there another mouse out there that has the same middle button function? This is most important to me.
 
Well you said you're not using it for games, but the side buttons can also be assigned a lot of different functions. My girlfriend has one for school and she loves all the shortcuts she can program into it