Panasonic EFC (electronic first curtain) shutter mode

Has anyone ever noticed SS issues using EFC on a Panasonic body?

I recently bought a G85 and was happy to see it offers the option of electronic first curtain shutter. With EFC the exposure is started electronically and ended with the mechanical shutter so in theory shutter shock should be eliminated.  And in my testing it does.

But the imaging resource review of the 200 f2.8 includes a comparison of mechanical, EFC and electronic shutter modes on the G9. There was no difference between the completely mechanical and EFC shutter modes with the results of the completely electronic shutter mode being noticeably sharper.

I am curious if other people have looked at this and if your results agree with mine or the IR testing.

With the GX7 I used to own the mechanical shutter was so loud and prone to shutter shock electronic shutter was my default choice. With both the G85 and GX85 I have now the shutter is so quiet and has so little issues with SS that mechanical (GX85) or EFC (G85) is my default choice.  Since EFC is not an option on my GX85 I will switch to electronic when using long lenses at certain shutter speeds.  But with the G85 and EFC if I switch to electronic it is not because I am worried about shutter shock.

My 100-300 is the lens I had the most shutter shock issues with.  These 100% crops were taken in manual mode with IS turned off and with a solid tripod.  I forgot to switch to manual focus but in the past have got the same results as when using MF.  The 100-300 is not as sharp as the 200 f2.8 but the difference between regular and EFC is noticeable while the difference between EFC and electronic is not.  And all of them are a lot better than what I got with the GX7 at the same shutter speed using its mechanical shutter.