I'm 5'9" and bought a Trek Madone 3.1 wsd in July. I had a terrible time trying to buy the bike. I went to 5 different stores and three did not have any 56 wsd bikes for me to ride. One guy put me on a 60 (not wsd) and dismissed my concerns that it felt unwieldy. One guy told me he could order one, but the understanding was that I would buy, not try. Finally went to a place that listened to me, swapped some stems on a regular 56, let me ride some more, listened, swapped stems, etc. Eventually I ordered a wsd from them. I love her.

I wouldn't worry about the floor model. I don't think road bikes get too beat up during demos. See if you can get a discount.