If u want sheer power, P4 is always going to be better than P-M. however the XPS2 has a much better VPU then XPS, so overall i think the XPS2 is alot better then the XPS, as it has longer battery life and better VPU.
The XPS2 will be...
a bit of light leakage is normal, tho its possible to find a laptop wif zero light leakage, i wldnt go thru the hassle of replacing my screen unless it significantly affects the quality.