I dont recommend IEO or even Any coin offering in crypto ecosystem. The last that that i participated in ICOnwas a disaster and i lost all the money that i ever accumulated here by participating in signature camps, plus i lost the credibility because of two mishandling of loans. All this happen because of sending my money in exit scam ICO.
Stay away from ICOs and IEOs.
I am bitter to hear about your losses, but not everyone has such bad experience investing in IEO. The above listed exchanges, all but bittrex, brought good income to their investors who participated in the IEO sales.
Statistics according to, for example, Binance, speaks for itself, it is easy to find on the network.