Ordering shouldn't put you at much if any of a disadvantage in terms of negotiation compared to buying off the lot unless the new car has been sitting there for a while and they're trying to move it. Dealers actually like ordered cars precisely because there's no risk that it'll sit on the lot taking up space and depreciating because no one wants it or likes the car but goes elsewhere because it had the wrong options. Ordered cars come off the delivery truck and go right out the door, freeing up space on the lot to keep another car in stock.
FWIW I worked with Chris Markey at BMW of Austin last February based off forum recommendations, and he was fantastic. I did some research and found that at the time people seemed to be getting $750-1000 over invoice, and since Chris seemed to be a good guy from what I read, I decided that $1500 dealer profit over invoice sounded reasonable to me and should avoid the whole bargain/haggle phase. I emailed Chris with that offer, he emailed back within an hour to accept, and that was the final price of the car (plus Training and MACO fees, which aren't typically shown as part of the invoice pricing you find online but are considered part of the dealer's invoice cost). I didn't try to talk him down further later, and he didn't say yes just to get me in the door and then try to drive up the price. Could I have gotten a better price? Maybe, but I've found that if you try to squeeze the best possible deal out of good salespeople, there aren't as many good salespeople after a while. I may have paid a bit over average, but I was happy with the price and Chris gave me a great experience before ordering, during the wait period, and even after delivery -- including handling having my car taken to one of the top paint shops around to fix two TINY paint blemishes from the factory that I never would have noticed on my own. If paying that extra amount was partially responsible for the treatment I got and helps keep great CAs in the business, then I'm fine supporting that.
Remember, the difference between $500 and $1500 over invoice is hardly anything from the buyer's perspective on a $70K car percentage-wise, but it makes a HUGE difference for the CA.
If you go with Chris, tell him John Hughan referred you.