OP, I see your point. The message is kind of sad
. You are loosing long term faith in canon. You are basically half expecting to move to Nikon may in 5 years, or in 10 years, or in 15.
Once you are going the path of manual focus definitely you have precluded fast moving subjects. However, if you are very efficient in manual focusing then probably you can still do those objects. (as from reading other posts of other posters here it appears to me that many of them actually prefer to do manual focusing with fast moving objects). But for getting the focus confirmation you would need to buy the Nikon-EOS adapters with focus confirmation chips. Other than that I do not foresee any problem with using Nikon mount lenses with Canon. In fact I want to buy the Nikon 50mm 1.2 lens in near future (as the canon version is out of my reach) which is a complete manual lens even in Nikon mount (so technically in your situation). You are already willing to forgo AF and going for the high quality glass of Zeiss (just read about it, never used myself), therefore, I am not sure how you would not be able to take the benefit of DSLRs (as the other replier has said), especially when canon can do stop down metering. To add from personal experience, I sometimes use a Pentax manual lens with adapter on my canon bodies, never faced any problem till now. Even the cheap non-chipped adapter is well machined and a snug fit to both the lens and the camera mount. Everything is manually controlled - aperture and focus. Added a ebay dual 45 degree split microprism focusing screen (brightscreen and katzeye too costly, at least now). I guess if you are buying Zeiss you wll definitely buy brightscreen or katzeye focusing screens which will perform even better than my cheapo focusing screen (not that mine is doing badly for me). So I do not see your problem.
But, die hard canon fans may not be happy at your decision, given that you are standing at the door between Canon and Nikon rather than strengthening the ranks of the Canon users
. I would say smart move.