1DMk4 or 7D?

[fess67]

Looking to 'upgrade' my 'sports / wildlife' body.

Currently have 50D and 5D2 so looking for a replacement for the 50D. Not unhappy with the 50D but found low light an issue at times so really looking to solve that problem. Question is, is the 1DMk4 that much better than the 7D??

I have done a comparsion below. Not much between them on paper really, 2 fps but offset by the slightly longer reach of the 1.6x crop on the 7D. Will the additional AF points make much of a difference? What is the practical difference in the high ISO capability? Enough to justify the cost??

Would I be better going the 7D and getting another long lens? - I have the 100-400 but was looking at the Tamrons or Sigma lenses out to the 500mm range - Are they any good?? They come in at $1000 - $1600. Would push me out to the $4400 mark.

.....It is ok going out to 500 but at f6.3 we come back to the light issue so is the 7D going to be ok at the higher ISO settings (in terms of much better than the 50D or much worse than the 1DMk4???). Soooooooooo...........is the 1DMk4 the correct option? - plus the other (probably too many) questions lol Help required

1DMk4	7D
10fps	8fps
1.3x	1.6x
45 point AF	19 point AF
16.1 Mpix	18 Mpix
$4700	$2790 (with bty grip and 3 extra batteries