As an investor, i cannot participate in IEO conducted by small and new exchanges. The main reason why IEOs are preferred to ICOs is because they are more prone to scam than ICOs, and this is because the exchange validates its legality with their reputation. Imagine Binance or any top exchange conducting a scam project, it will jeopardize their integrity, and these exchanges do not want their integrity in question, so they only offer legit and promising projects IEO. New exchanges do not have the reputation to validate a project, they are just after the profit, SO they might promote a scam project either intentionally or unintentionally.
IEO organized in small exchanges is very risky because little exchange does not filter out real projects or they just want to earn money and profits do not think about the fate of investors who spend a lot of money to buy tokens fraud. Investors are now getting smarter they prefer to invest in large exchange binance and okex.