Thanks for all the comments so far! Dr Fill, yes I did replace the background in Georges shot, the background just didn't do him justice and it was shot in my bedroom with only on camera flash. I totally agree I think the blending is most obvious on the right hand side of his face but not bad for a first attempt at a total change of colour. Practice makes perfect!
I also concur that the white balance is off on Boris' shot. the original was flat and uninviting but i think i may have oversaturated it. This was the first photo I took with my first D-Slr and I think i'd do it slightly differently now ie. smaller aperture etc. I will have a tinker with the saturation and wb
As to making George portrait, i'll have a go and see what i think. My intent for this shot was to put it on canvass for the owners birthday and I thought it might look better as it is A1 size. Still, I do take the point about framing.
Great to have criticism from other snappers! 