sony a77

Hi, i was wondering about change my Canon equipment for Sony a77, with 16-50 2.8 and a sigma 70-200 2.8 and maybe a 50mm 1.8, i have now canon 60d with 17-85 4-5,6 is and tamron 70-300 with stabilizer..any thoughts about this change of brand? what will i gain ? i photograph everything..but a lot sport..thats one of the reasons..a77..i think..seems a lot for the money..

hopes for some advices..