2011 Mac Mini 2.5 Ghz or 2012 Mac Mini 2.3 Ghz quad core?

I intend using it for Lightroom 4, Photoshop Elements 11 (maybe PS in the future) and Finalcut X or Premiere Elements.

What I can't figure out is the graphic card side. 2011 one has AMD Radeon HD6630M GPU with it's own 256MB of video memory and the 2012 uses the integrated Intel HD4000 which would borrow 512MB if I had 8 GB of Ram on the computer. Which will benefit me more? I won't be using it for games at all. Also if I upgrade the RAM to 16GB I assume that will give me 1GB of video memory when required? Is borrowed video memory going to be as good as dedicated video memory?

Also with either option what happens if the video card goes wrong? This has happened with my Powerbook and as because it is built into the motherboard it is not worth repairing. With the 2012 one would the processor just need replacing or the whole motherboard? As the 2011 is separate can that just be replaced?