I would go ahead and book, You don't have to put any money down upfront so if plans change you have up until 48 hrs before your reservation to change it without a charge.
I am booked through their website for July 31-Aug 6 and I have the DIS rate and if the ENT rate comes up I will email the hotel and ask for that rate. I already emailed someone there and they were very friendly and got back to me very quickly.