Thank you, Jakov!
No second thous about Sigma, is just good.
750-I was looking for good AF, because using very often combo 200-400 with TC-14, plus my age-good AF is the must. And I think, AF is better than in 700 or 600/610, plus 24 Mega, good high ISO(my hare pix...), decent 6.5 frames/sec.
Maybe somebody else will chime in....
And