Legit project would prefer IEO than ICO. they don't need to market their product publicly as exchanges running the IEO will be the one to do this for them in short bounty would not be an option anymore for them or if they do the payment for bounty would be cheaper since they will pay on exchanges that will cater the IEO.
Yes, this is very effective, namely implementing the IEO when ICO is very bad now, every IEO project at the Binance market always sells very successfully, so the presence of the IEO in the Binance market is very good for making safe investments.