As you know IEO trend is growing but i feel IEO is profitable only for those who invested in token sale but who have purchased altcoin after launched they suffer loss majority of the investors ,as the BTT and some other altcoin examples of IEO.
The problem about ICO is that most of them are failed projects and are not listed in the exchange so you are stuck with the priceless coins in your wallet. IEO is not that more profitable than ICO, it is just that the coin is listed in the exchange. By doing so, even if the project does not meet its promise deal with the investors if earning a lot more than the capital, at least your coin will be not stuck around your cold computer forever. In IEO, you can minimize your losses faster than waiting for the exchange of the ICO.
Problem by ICO is delay for listing, I got many ICOs coin listing after one years ICOs ended and many people less trusted with ICOs investment and try for investing with IEOs project because can listing faster than ICOs, now many people have left and interested with IEOs because not have waiting one year for selling coin from IEOs investing, just few weeks they can take profit or lost with IEOs coins.