Nope. Can't afford both. Well I could, but I have the money tied up in big, heavy glass at the moment. And I like the glass a lot!
This is a known issue, I recall Chuck Westfall saying that the tradeoff for the high performance Area AF sensor in the 1D was the slightly lower sensitivity.
This is actually a perfect compromise. We have the 1D for action-stopping daylight work, and the 5D with its ultra-clean-high-ISO and better AF sensitivity precisely for those situations when we need to shoot in the dark.
Yes, the 5D is more of the night camera. On occasion, I find the limitations of the larger AF sensors can be a hinderance, but that is quite rare. Only with a small subject, and a busy, contrasty background. The 1D2 is susceptible to this as well, but the subject needs to be even smaller relative to the background. Smaller, more precise AF sensors vs. larger, more sensitive sensors.