The sofa is now in my apartment. Once the legs were off, it went up the front stairs easily, or at least easily by basement-to-second-floor-sofa-moving-standards. Thanks to Matt for helping me move the sofa; Karen for providing objectivity, encouragement, and mad screwdriving skillz; Madame Bequerel for telling me to quit screwing around and use a drill; and Paulette for rightly reiterating to me that if you are going to start disassembling something don't be halfway about it.
Now, I need to go about reattaching the legs, which will require a trip to a hardware store for which there are also various other items on my list. Before I go, however, let me reaffirm that I am not a person to be trifled with, at least not by any members of the Pottery Barn Grenwich line. You may win some opening battles, but, so long as I have good friends, power tools, and my newly indomitable 'tude, you will lose the war.