al Asaad

The only real "crop factor" that counts in imaging (any) is the "cropped" viewfinder.
A less than 100% viewfinder is an imaging handicap.
Let us say the image you need/want is in your viewfinder. You've carefully composed your image, taken a deep breath and make the shot.
"Drat"!

There's a limb-person-beer can-you hadn't noticed in the viewfinder but magically, the culprit has crept into the edge of the frame, destroying all your carefully planned efforts.
Worse, before you could get another snap, the moment had passed.
*Letting parents pose their babies for instance: the baby cracks an irrepressible winning smile and mom's knuckles are sticking around on the edge of the frame.

With my Evolt DSLRs (E500 & E510) there's not that much of a problem: go into post-processing and crop the offender out or modify the content of the image by simply removing her knuckles with your clone tool.
But even that solution is a problem for those of us who shoot for hire: the glitch in the less than 100% viewfinder could mean cropping out a critical section of the image.
Even worse for some of us who shoot for publications: a less than 100% viewfinder means the "white space" needed for copy in the image is gone: vanished; kaput.
*The worse offender of less than 100% viewfinders are 16:9 shots and/or superimposed panorama frames where all sorts of "suprises" show up, many of which cannot be seen in the 2.5 and 3 inch LCD screens of most DSLRs and all point and shoot cameras.

So sensor "crop factor" or not, the only "crop factor" that really counts is bad-dim-less than 100% viewfinders.
There, the photographer has to be totally aware of their camera's viewfinder limitations when composing to make the best of a bad situation.

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