In the Stenstrom article from the Arda Annual he actually does some sketching using horses with their noses at his shoulders and estimating Bilbo between 3' and 3'6" and normal body proportionality and comes up with a conservative estimate of 10'. It also speaks of the other descriptors indicating size within the chapter Queer Lodgings.It's funny but it is how I always visualized him from my readings before coming across this article.
Beorn always stood out to me as something of an anomaly in the Tolkien Legendarium much as Tom Bombadil. As far as we know, Tolkien never revisits Beorn in his vast writing on Middle Earth or attempts to fully define or place him but does legitimize his presence by mentioning him in Fellowship.
Here is another great online essay on Beorn that I find very informative.
http://www.thefreelibrary.com/Beorn+...es-a0163972510