LOB THEM ALL ON!!! haha
I suggest taking the genuine closing panel apart and the M-machine one too, thins is because the mating surfaces between them both will be bare Metal on Metal contact with no primer or paint protection so best to drill all the spot welds out and re-do them with zinc primer protection or similar and then use whichever you like :)
Having just removed some original ones of these and i can vouch there is no paint between them so worth doing. Then i would edge seal them as well.
One thing that M-machine doesn't bother doing then 
Sill....makes life easy when there single panels instead of having that black coating to clear off
what a pain in the
haha
Something i found to be good was the adesion paint has when sandwiched wet, i mistakenly made a wet paint sandwich with two metal pieces and found the suction alone tuck them together pretty darn good so maybe you should drill some holes for plug welding, rub them down, zinc prime the surfaces and brush paint them also before sandwiching them together and clamping them in place and then when its dried you can plug weld them back together :)