I think you should use only one of platforms.
In this way, after ICO, there will be two kinds of tokens. One in ethereum platform and another one in waves platform. It will be confusing.
Waves is a good platform. In my opinion use that for both pre-ICO and ICO. There will be no problem.
Thank you. Actually I was thinking about exchanging Waves-based tokens to Ethereum-based tokens afterwards. Not sure that it can be done transparently for all the participants though.
That sounds like a lot of trouble and then you will be subject to moral dilemmas that can affect your reputation, for example it is not rare for scammers to get coins of early investor by deceit, but what would you do if the owner of the coins say to you to give to him these ETH tokens even after he got scammed? And what if he sold the coins and now is trying to scam the new legitimate owner of those coins.