So I've had my faithful 5D Mark 3 for 3 years. Love it.. such a great camera. I was excited for the Mark 4 to come out - but I felt that it got a lukewarm reaction at best and that tempered my excitement - so I haven't rushed out to buy one to replace my Mark 3. I have noticed some photographers upgrade to the Mark 4 from the Mark 3.. so I would like to hear form anyone here who's upgraded from a Mark 3 to a Mark 4. Do you like the Mark 4 more? Any advantages? Is it worth the investment to upgrade?