Mono/Stereo output question???

[pjackso]

I just read this on Harmony-Central (referring to the H&K Rotosphere MK2):

"(when using in mono) you'll get a more intense effect signal if you use the left (stereo) output.
the trick is to set the plug half way into the jack. this engages the stereo output. the end result: authentic Leslie tone in a portable, affordable (compared to a cabinet) unit."

MY QUESTION: Is it safe to use the left (stereo) output with the jack halfway in?
Why does this happen?  The signal certainly seems stronger and the sound seems better than simply using the mono (right) output.
If this is true could I run the right (mono) output to my tuner?
Thanks for any info you can give me