50/50 has wider stance, I'd say by maybe 2 inches, one can definitely feel the difference. 50/50s are also longer and narrower. Flex feels very similar, both boards are extremely smooth.
NHP would be a better choice for all around, amazing board, does everything well.
Not sure about Shinn being evolution to Nobile, if I'm not mistaken, Shinn boards are made by Nobile in the same factory. I'm sure they keep their finger on things
Go for NHP, many guys say 2013 NHP is the best yet.