Currently using the Lowrance Mark 5x with the siliconed-in puck a la Kingfisher's conversion to portable (8AA batteries).  Works great for me!  So good that I bought a 2nd 'ducer to mount in the solo canoe.

I really like the ease of portaging without having to do anything other than just turn it off and rotate the unit down, then just rotate it basck up and turn it on again on the other side. 

95% of the difficulty of portaging lies on either end of the portage.  The actual walk is cake in comparison.  Anything I can do to streamline the process on the ends is absolute gold.