D800(E): The Sigma question

I have come across some interesting Sigma lenses:

1. 50mm f1.4. Seems to have alot of character. Corners very soft until f8

2. 24-70mm f2.8. Could be useful for non-serious event photography (e.g. childs party). Very mixed views on the net, some people say sharp in the centre at f2.8, others say only sharp from f4. Other comments are the wide end is better then the long end

3. 85mm f1.4. A lot of folk seem pro this lens, particularly on sharpness

4. 70-300mm f/4-5.6 DG OS. not heard anything about this. A good cheap substitute for the nikon 70-300mm for occasional use only ?

any comments from those that have used any of these on the D800(E) ?

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