the old 5D mkI

I came across deals on refurbished 5D bodies, and was wondering if the full sensor at 12.8mp would be a step up from the 60D APS-C I use now as to Image Quality. I'm not a pro, and don't make huge prints either.

of course, I'd get to up grade most of my lenses too.

or should I just keep saving my lunch money to buy the MkII or new MkIII ?