A decision has been made! - well 1/2 a one anyway.
I'm going for Full frame and the the 5DII so at least that side of the equation is locked in.
This leaves me about $600 for the lens.
I have had a photographer friend test a 100mm lens and confirmed that the tight, just below chin to middle of forehead portrait that I'm after would require the lens to be about a foot from the persons face.
For 1 or 2 shots this wouldn't be such a problem but as it is the majority of shots I want then it would be a bit too (literally) 'In your face' to be acceptable.
Therefore I am now looking to something up to 200mm or perhaps even more, which with my remaining budget I'm having a hard time ignoring the non-canon options. I'm reasoning some of their latest higher end offerings should be better than canon's quite old low-mid range lenses in this same price sector.
I was hoping for a used Canon 70-200 f4.0 IS which has a reasonable MFD but they seem to fetch around $,1000 so not much cheaper than new anyway.
I also think stabilisation would be essential for me, especially at longer focal lengths outside, on the move. I have gotten quite spoiled by my little Powershots excellent IS.
PS. Kirillica, where are you? Don't be modest