I use Beyerdynamic 990DT headphones over two BTE hearing aids with no feedback. Maybe the cloth covering is gentle enough not to cause it?

https://www.amazon.com/Beyerdynamic-990-Premium-HiFi-headphones/dp/B00193FT26

I haven't had a chance to play the Stage 3, but I recently purchased a used Nord Piano 2. After a solid month of doing research trying to select the right digital piano upgrade, I went to a local shop with every intention of buying a Yamaha P515 but when I sat down an played it, the action felt clunky.

After trying a few other options in the price range, I went with the Nord. The action is perfect and it's amazingly simple to use, despite the buttons and knobs looking really complicated.
The ability to download sounds and completely customize everything is amazing once you start understanding it.

I mostly play using headphones (although some pretty pricy ones - Beyerdynamic DT 990 Premium Edition 250), and and think it sounds amazing. I'd suggest getting a nice pair of open-back headphones if you intend to practice a lot. Something like the Philips Audio SHP9500 (https://www.amazon.com/gp/product/B00ENMK1DW) are nice and reasonably priced.