As I understand, unsold tokens will be burned? If - yes, then this is good decision. "revoke = burn? "
It is more correct to distribute unsold tokens in proportion to all holders in proportion to retain the original percentage of bauntists and investors.
i suggest to already make one other currency so that they no longer need to send you a pm dev and they can send it right away if they want to invest. why not try to have it already in your ico site to reduce hassle for investors.