Does anyone have experience with this portable Morse training device, or
others like it?

It's depicted he
http://home.austin.rr.com/jfisher2/MCD.htm
K5JHF told me that no inventory remains and he does not plan to make any
more. I am curious about how useful it proved to be for gaining and
improving Morse proficiency.

Portability seems like an advantage, enabling the device to be used while
driving, exercising, etc.

Tom, N3IJ