But for many the audio you hear also gets degraded. Like when Windows sets it as communication device instead of headphones and it sounds like a 64kbps mp3s
So yeah, the isochronous streaming mode is much lower bit rate but thats probably why Windows sets it as a communications device, because it needs that mode.
Its difficult to know exactly, but I use a Logitech Zone Vibe 125 headphones with microphone and find it works fine for phone calls and listening to audio. However, I am not an audio nerd and neither are the people I speak to using it. I never had any luck with in-ear devices.
mSBC is worth a try if you haven't already tried it, but it's not a real solution. Bluetooth LE Audio does provide a fix, but real hardware that supports it is hard to come by.