I did ED a few years ago on my 330cic, and have talked with several others. In my case, and most others, the dealer said the only discount was the 7% off of list, and all options are at list. No other dealer discounts could be negotiated.
With that said, one or two others claimed to negotiate additional dealer discounts beyond the 7%. According to my sales rep, the dealer makes some $$$ on ED, but not as much as compared to a regular sale, so no additional discounts. He said ED cars do not count towards their sales quota, so they don't get dealer rebates, etc. on ED.
ED is still worth it, unless you can negotiate a really good deal.