I am going to replace my 5 speed maxxum with a variable speed.  It looks like it can be done using the existing mount by pulling the two pins, removing the old, align the new, replace the pins, and wire it up.  I see no reason to remove the entire mount if not needed.

Has anyone done this?  Anything I'm missing?  Can it be done by one person? 

That's about right. I have had mine off the mount several times. It's pretty simple and easy. It's a one person job, and I find it way way easier to do it with the motor in the "deployed" position, you might have to raise the motor up high in the mount so the lower unit doesn't hit on the trailer hitch. You will get a new mount with a new TM, but unless your mount is beat up, or getting sloppy , you'll be fine just swapping the motors out.