I previously owned Canon 5D Mark II, sold it and bought Sony Nex 5 and upgraded to Sony Nex 5N later. I use Lightroom 4 for processing RAW images. I think rejections are about at same level than with bigger camera.
I use a Panasonix Lumix DMC-G2 micro 4/3 which when matched with the 20 mm (40 mm equivalent) "pancake" lens is very compact. I have very few issues with images taken with this camera - I develop with Lightroom 3 and keep the ISO low.
I also have the Lumix LX5 which has a very nice, fast Leica lens. I've reviewed this camera on blog - Keep in mind I have had more issues with images from this camera not being accepted than with my larger camera.
to my opinion I would say that for stock photos you will have an issue with compact cameras. Those geeks have small chips (in terms of area) and thus the digital noise is much higher than this of DSLR. To stay competetive you nedd to buy high end compact to achieve good technical parameters for acceptation. I guess you can buy a low end DSLR such as NIKON D3000 or CANON EOS1000 istead, even second hand. It gives you much more value it terms of future development (acessories, lenses, speedlights etc...) of your system or residual value in case of sellout and upgrade.