Squirreled away on my website are two old icing accident reports that may be of interest. Both involve DC-3's, obviously, and both investigations conducted some flight testing with associated discussion of the DC-3 stall characteristics. Pretty interesting for a variety of reasons, but may be of use to this thread.
http://flightopsresearch.org/data/files/united21.pdf
http://flightopsresearch.org/data/files/northwest5.pdf