I know we have discussed mirrorless vs dSLR several times. But this is a well thought out article specifically regarding FF mirrorless by someone that has heavily invested in both:
http://petapixel.com/2016/04/04/sony...fatal-mistake/
Its interesting as now that Sony has released the "G" series lenses, much of what has been foreseen is reality. Sure you can make a smaller body, but to get the light gathering ability and to project a FF image circle, you still need a large lens. I actually thought there would be some savings in size/weight. Turns out, as designed, not really.
And that is only meant as an observation. If someone is happy with Sony, great. A one time contributor to our forum wrote about his switch to mirrorless awhile ago. Granted, that was to an APS-C body and the above review is FF.