As for AF dictating composition, yes, it could, particularly if you are shooting under low-light situations and don't separate AF from shutter release functions.
I would like the interchangeable screens feature to be really easy to use, similar to changing a lens. If you look at the number of specialty screens for Canon 1DX, maybe eight or ten (mmm - but ONLY for that model Canon, not the low-priced ones), it is clear that Canon does indeed intend to make its pro customers happy. Split prism, superfine ground glass, all-over fresnel, grids, and more variants are available. I can switch screens on my 6D,with a superfine ground glass option and a grid option only. Superfine ground glass is great if you have fast lenses. I am mucking about with f/5.6 lenses, occasionally with teleconverter for f/8, and I have exactly one lens faster than f/2.8. I would love to be able to alternate between AF standard screen (slow lenses) and ground glass (fast lens, maybe lenses in a bit). Live view is for static subjects and for checking zone focusing. LV is totally non-ergonomic for real action.
All of my AF lenses have AF/MF switches, and they all offer "full time MF", a must for any AF lens that I would consider.
I have been trying out my closet of legacy lenses, all manual focus manual aperture, and am having fun. My current fun lens is Mamiya-Sekor Macro 60mm f/2.8 with preset aperture (for 135) - really ODD bokeh.
As for birds in flight, AF is great. Because I am shooting BIF for my own interest, and not to sell, I don't Care that it might be a cliche. I have also used MF for sitting or standing birds and occasionally BIF when using my 1.4x teleconverter for effective f/8.