I recently saw this on my amazon.com recommendations. I already have a copy of the enhanced edition here on GoG.com (and like it) so i was wondering if there is any reason to get the platinum version (besides having a physical copy)? I like having all the DLC and extras.

There never was any in game content that was exclusive to any version. As for bonuses, I haven't seen an English version of Platinum Edition, but I'm guessing it's the same as my Polish "Platynowa Kolekcja". As far as I know, you are not missing anything (I'll make sure later).

Edit: What seems to be missing in GOG extras is the fan-made stuff.