You get Sony "quality" with both cameras.
As megapixels increase, the lenses are struggling to resolve these huge amounts of pixels. Those lenses arent any bigger than on 3mp cameras.
Just look at one of any of the popular dslr cameras, with the huge interchangeable lenses but still only 6mp or 8mp ccds? Theres a reason for that.
So with that in mind, extra pixels make bigger pictures but not necessarily better pictures.
i.e. Ideally extra pixels make better cropped pictures if the need arises(useful), but a loss in sharpness, so post process sharpening will be required.
I would go for the camera which answers all your requirements and forget about ccd resolution unless an A3 print is an ultimate requirement: for most it isnt.
Size and features are the two most important, dont pay for extra pixels if you dont need them. Most Sony has hologramatic low light focusing sensor, thats neat and it really works.
Sony doesnt make crap cameras. Go for the feature set that meets your needs. Be happy in your decision.