The EOS network will use Graphene (special transaction as proof-of-stake technology) used already by BitShares and Steem.
Concerns
Still under development with no clear deadline or progress report.
Proof-of-stake governance could fail if not enough stake holders vote.
Since the same EOS is used for both staking AND bandwidth it would require a delicate balance between the price of the different services. EOS should not become too expensive to run any smart contracts or but should also not become to cheap that the reward becomes too low to run any nodes and should still be profitable for investors.
With the largest and longest ICO in the world, investors might have over-invested into EOS so that there are little investment growth opportunity left after the ICO.
A competing smart platform could win the race and make EOS redundant.
DISCLAIMER: This is not investment advise. You should do your own research and I cannot guarentee that all the information on this page is still relevant or 100% correct.