Originally posted by fccwpe
However, you won't get the same backward lens compatibility or in camera SR (other than Sony).
fair point about SR, but I shoot pentax and canon- and my canon takes pentax, nikon, m42, olympus and many other lenses
the k mount compatibility is not that much of a selling point anymore, yes you get automatic stop down on a pentax body, but unless you're shooting f11 in the dark you can still see fine on the canon (and the canon viewfinder > pentax viewfinder)
also on a full frame canon the noise control is 1 or 2 stops better than the k5 (yes, it really is), which counter acts the in body SR
and this is the kicker, flash control- you get full E-ttl automatic flash control when using pentax lenses on a canon body- you don't even get that on pentax!!
although for the price of the canon I could have bought 3 k5's,
the canon is also huge, unsubtle, and heavy
so they both have their merits- but for me, pentax's strength is not absolute performance, but performance at a price- ergo you're likely to see more issues. If you can afford the canon system then go for it, but if not, then stick with pentax. Just depends on what type of photography you're going to be doing.