i just stepped up from a 7D (i still have) to a 6D (got it on monday).
like the OT i had a EF-S 10-22mm i sold for a good price.
im very happy with the 6D image quality (table top, portraits, landscape).
definately noticable better then the 7D.
the 5D MK3 focus system is overkill for me and for sports i still have the 7D.
maybe if i had a 400mm f2.8 or 600mm f4 i would buy the 5D MK3 for it´s AF system and BIF.
wifi and gps are a big plus for me.
im a metadata freak and i tagged all my 7D images.
the 6D makes it so much easier.
took some bird photos with a remote setup already.
6D plus a nexus 7 is really fun.
now i can see the liveview and focus when i take photos with a remote setup.
before that it was more like playing roulette.
but im struggling to get a replacement for my EF-S 10-22mm.
a good wideangle landscape lens.
i rented a EF 17-40mm and a EF 16-35mm this week.
the EF 17-40mm border quality is not what i expect (not even closed down to f8-f11).
the EF 16-35mm cost twice as much as the EF-S 10-22mm and the image quality is at best equal.
i guess i will buy a used standard zoom (EF 24-105) at ebay and buy a new EF 24 2.8 IS for landscape work.
the 24 f2.8 IS seem to have the best image quality of all wide angle lenses i can afford.
some time next year i hope i can afford a 24mm TS or maybe canon will release a really great 12-24mm lens some day.
going FF was definitely a good move for me.
i knew i have to buy good lenses for FF.
but even the 17-40 or 16-35 are not that impressive if you ask me.
i think canon has to improve the EF wideangle lenses.
that said i absolutely love the 6D with my 100mm f2.0 and 70-200 f4.0 IS.