@WaseemAlkurdi: I don't have access to my PW1, and I'm way too lazy to check the final PW1 sources, but that sounds sensible

.
The most notable differences will be the touch input (IR -> capa) and lighting (ext. port -> FL).
TL;DR: PW2+ FW is probably a no-go (req. 2.6.32), but PW1, eeeeeeh.
Which begs the question: is there anything at all worth the trouble between 5.3.7.3 and 5.6.1.1?