The Canon 6d may not have the sophisticated AF system of the 7d (I have both) but the picture quality from its Sensor & Digic 5+ processor is far superior.
In low light the 6d excels and Ive yet to encounter any real world problems with the 11 point AF system (the 7d having 19 which are all cross type whereas the 6d only has a centre cross type)
Im sure Canon will replace the 7d in 2014 and at this stage no one knows its specification but if it were me I would not bother repairing the camera if its expensive.
Canon 6D, 16-35 f4L IS, 17-40 f4L, 28 f2.8, 24-105 f4L, 100mm f2.8L, 70-200 f4L IS, 70-300 f4-5.6 IS USM
Canon 7D, 10-22 f3.5-4.5, 15-85 f3.5-5.6