Gaming mouse for my girlfriend?

Hey everyone. I have a G502 Proteus Spectrum and I love it. My girlfriend has used it and loves it too but her fingers are too short (she has small hands) to reach the G6 button. It's the default DPI shift button. She wants a new mouse that also hasthat button so she can bind abilities to it. Are there any other gaming mice you guys can recommend that have similar performance and button layouts to the G502 but might be more friendly to those with smaller hands? We're not too worried about the price since we have a Newegg gift card. Thanks in advance!

edit: Link to G502 layout so you know which button I'm talking about. http://d2rormqr1qwzpz.cloudfront.net/photos/2014/04/14/60001-g_software.jpg