Why would you want a DotEMU botch port sullying your Steam library?
Better stick with GOG for them.
I have both games on GOG, the problem is I find REALLY hard play LBA those days. I'd take the new version just for the checkpoint system and the fact you can now see exactly where you land after a jump. I tried to play GOG version, I found it really hard.
Also can DLCs for MGSV can be purchased with MB coins?