I have SE5 on Steam already, but that version is seething with bugs! It also does not work "out of the box" and requires you to manually create ELEVEN empty directories that the Steam installer misses. Or it was like that a few years ago when I last played it.

So is this GOG version better?

Betterish. Try setting the memory amount to "safe" though. Space Empires V was not designed with 64 bit memory amounts in mind.