My experience is that under good outdoor light, and shooting in lowest ISOs (80, 100) , coupled with good basic understanding of photography techniques, a P&S can easily produce stunning pictures suitable for microstock.
And with a pro DSLR like EOS-1D series with L lenses (not all of them are weather-sealed), they can probably withstand the abuse, but needs to be brought to the service center for more frequent checks and cleanups just to be on the safe side.
Like leaf said, how much are you willing to spend on this venture?
cheers.