Electronic first curtain
I have an NX200 and recently I've started to run into issues with shutter vibration (usally from about 60 to 180 but sometimes even with longer exposures). This happens mostly with longer lenses (even on a tripod). It also doesn't help that it doesn't have a remote shutter and I have to use the timer. On one of my cheaper tripods I can even see the camera wobble after it opens the shutter (using a timer). My NX100 does not seem to have this problem and my wifes Canon has a first electronic curtain (in live view) and is vibration free.
Now I've heard the NX20 has an electronic first curtain and supposedly the nx300 as well. However I can't find any confirmation of this (on the NX300) and I think it something everyone assumes. Can somebody check for me. Just set the exposure to 5 seconds or so with the lens cap on. When you press the shutter there should be no sound (maybe a little for the aperture stopping down) and no virbration (I can definitely feel it when my nx200 shutter goes). Better yet if you have a maual lens adapter you could take off the lens and actually see that the shutter doesn't fire.
As a side note I notice that the 30 shot burst mode on the NX200 uses an electronic shutter (no real shutter movement at all). Pity there's no raw and everything is half res.