GDK is lagging behind by several patches. It also has a much smaller user base and as I've found out recently, this means undiscovered bugs.
My personal feeling is, for most games you should stick with DBP. For more complex games, go for GDK, but expect a few minor problems and limitations and obviously much more complexity coding the game. It's all down to the individual as to whether the positives outweigh the negatives.
I will always use DBP for prototyping and quick apps. It's so much better for that, but I would never make Carnage in it. A procedural language without complex data types and the lack of easy incorporation with industry standard C++ libraries imposes a few too many limitations for advanced games.