May be eth will grow till the last DAO day (it will be HUGE panic buy on the last DAO day) = fear of missing something (human nature)
As illogical as this may seem, especially since The DAO has a 28 day buying window and the first 14 of those will be at the cheapest price (meaning the last days are most expensive), I expect you will be proven right as people will just have to get in before its too late.
The DAO folks might well have set up the ICO bonus timeframes in order to avoid a short-term ETH pump. Price-wise, there's really no hurry to buy ETH if you want 100 tokens per ETH.