A good question, but I tried that with a Voigtlander VSL (1 or 2 - I'm away from home at present) and while the lenses should fit, the early Zeiss made and branded QBM lenses actually don't mount at all well to the camera - the mounts are subtly different enough. The later Rollei ones do - so as a body it would not work with the Sonnar and the Distagon I have. Which is a shame.
The irony of course is that the Canon's autofocus is incredibly fast - with the kit 35-70 it came with - so much so it beats the pants off the Nikon F90X and F80 I have and is considerably more accurate. I don't use AF much, but when I do I want what the Canon offers. So I shall be mounting manual lenses on it...
Film amateur with a few rangefinders - Leica III, M2/M3, Werra 3 and Zeiss Super Ikonta 534/16 medium format.
Apart from that have a Rolleiflex 3.5F, the odd Minolta XD7, Hasselblad 500cm, a Topcon Super D and an Intrepid 5x4 large format (not the half of it but I am clearing them out, honest).
I do all my own black and white developing at home.