You don't see the point I'm getting at H. Both cameras have the good and bad points and depending on your particular "bent" one is better than the other. But, there are always bigger and better beasts on the block. Even amongst either brand. For instance, your 5D Mk II is going to out perform someone's little 600D. Someone's D7000 is going to out perform my D3000. But your 5D MkII and someone's D3S or D3X will be fairly close.
Yes, it's true that some makes do handle some stuff better than others, but that shouldn't dissuade anyone from purchasing those other brands. It all depends on what you're going to be using them for, apart from astropics.
Here's another thing...what were the skill levels of those using either camera.
In any case, if you're smart, you won't use a DSLR for high ISO imaging through a scope. You'll go and grab yourself a CCD camera and be done with it
Jump into the deep end