This seems like a good solution. It gives buyers a better idea of what they are actually buying by enabling them to "bid" - and if they aren't getting a satisfactory price vs. the % of the token sale they end up with, their bid can automatically withdraw.

Sellers will still need to implement correctly - one key variable seems to be the cutoff of voluntary withdrawal. By eliminating "voluntary" withdrawal in the last third of the sale, it prevents whales from bidding some arbitrarily huge price and then withdrawing at the last second to secure a low price for themselves.