I can't remember how good my custom earplugs were with occlusion, but being a 26 dB reduction, I think there was a pretty mid level of occlusion effect. Nowhere near as bad as half a foam earplug but I still remember preferring not to talk.
The good thing with Earasers is you can sit them in slightly differently to give a varying amount of dB reduction in these lighter situations, then rotate and push deeper for some scenarios. Overall the occlusion effect is less and doesn't make me feel like I want to be silent or disconnected.
Maybe it has something to do with them being lesser dB reduction? I've never tried custom earplugs at a lower rating so I'm unable to compare that.
But with these being pretty much invisible, it's an overall combo I prefer.