I am in need of a Backup...

For my 7D,i Need it for mainly for Motorsport due to the fact that my 7D gave UP Once on mewith Electronic Problems whilst i started Shooting in the Race Track.
I have 2 options:
1)1D IV (4000€)
2)1DS ii (1300€)(& 2x EF Converter to Cover the fixem lenght)
Cons for 1DS ii Small Display,4 Frames per sec And i don't Know much about the AF Capabilities
Pros for 1ds ii i can breath Dome Full Frame Air
What would you opt for?

Cheers

According to your signature, you already have a backup camera in the 40D. Do you not need the frame-rate when shooting motorsports? I ask this because you listed the 1DsII as a candidate, whereas the 1D4 gets you the sublime 10fps.

Do you need more than 10mp? 1D3 could still be an option, though I suspect if you move towards a 1D(s) body, the 7D would become the back-up.

But push comes to shove, you could just get a 2nd 7D. That way, the transition would be seamless as you go from main to backup. OR, you get to stick the 70-200 on 1, and 300 on the other and get uninterrupted shooting.

Thanks for the Response,i am having some problems with my 40d it does Not like my 300 And 70-200 2.8,the AF Skips a Little too much And After servicing it ain't better so i would Not like to relay on it during a Race.
I don't tend to Spray And pray so i am pretty comfortable with 4 fps,i just Need a good AF,i want a Camera with about the Same Resolution As my 7d so the 1d III is Not in line as is the 5dii (Yes i tried it an was not satisfied with the results).As for a Second 7d well One should Be Open for New Things .
Thought i'd get a Little Hearing for seeing the 1d IV As a Backup for my 7d