The green and blue is nice, as are the overall proportions. I guess we're still looking to try and tweak things to involve an element of our medical specialty, although dealing with stomachs, livers, and intestines doesn't make for cool art like hearts, brains, and spines do.
#2 does almost have the feel of a stomach in the swirl with the straight line potentially representing an endoscope. We like the symbol in front of the name rather than under it, as well as the proportions of
#2 compared to
#4 and
#5.