Well, as-they-say... "ignorance is bliss". If you are happy with what you have, stop reading here.
Curious about all the various theories, I just did an extreme quickie test, hand-holding both a Canon-FD 135mm, and then the Lumix 14-140 zoom at about 135mm,
With the E-stabilization on, there was a sudden glitch: when holding the camera very steady, propped on a window ledge, the e-stablization caused a kind of sudden delerium-tremors. Strangely enough, as long as there was some minimum panning, it was ok, but when the image was steadiest, the E-stabilization seemed to freak out. This did not happen when the E-stabilization was turned off.
Agreed, this is an extreme case: how often would you try to hand-hold 135mm, but there you have it. The potential for "artifacts" with the E-stabilzation are definitely there, where it was not a problem without e-stabilization.
I will try to post the quickie test tomorrow.