In-ears work great on a plane, car, anywhere you need isolation. I have ER4P's and ER4S's but use blue foam earplugs with a hole punched through them for better isolation. The ER4S's have more extended & transparent highs but often need a portable headphone amp to drive them.
Curious how all the in-ears compare to one another. Anyone try several different types? This is a tough thing to try before you buy. I tried Ety ER6's years back before I picked up the ER4P's years ago but the sound didn't cut it for me after using the ER4S's.
I'm wondering how the sound of the other in-ears compare to the Ety's. I got my first pair 10 years ago. Back then the choices were more clear cut and there wasn't as much competition. Now there are Westones, Ultimate Ears, Shures, AT's, etc. and newer technologies like the usually higher priced multi-driver types.