Some PoW people even don't believe PoS is secure: https://bitcointalk.org/index.php?topic=615843.0
Is POI reviewed by any crypto expert and proven to be secure?
We are reviewing POI internally for now and testing multiple attack vectors. I think at some point all of the code will get an external review, but I am not sure.
POI should be more secure than POS because it should be harder to manipulate your account's importance. Despite what the POW people say, POS is fine as well. POI > POS > POW in terms of security, in my opinion.