I don't have experience with Sony, but I have used silent mode (electronic shutter) on my E-M1 several times recently. I have not noticed any flicker in most situations. (high ISO, open aperture, lit performances with pin drop silence) Then again, Olympus has a flicker reduction setting for the viewfinder. I did not notice anything in the photos under most scenarios, and doing slow shutter panned, or movement shots, I noticed no weird artifacts either.
When using an LED light table to shoot product work on, i DID get screen banding at certain shutter speeds. They were not in the photos. However, if I were to reduce my exposure heavily in lightroom I was able to see very mild banding pattern in the light table.
So far though, my results have been no different image wise from shooting with the mechanical shutter in these situations.