Should I upgrade it to Android 6.0 Marshmallow?

[shovenose]

I just got a new T-Mobile branded HTC One M8 that I'm using with Ting. Anyway, it showed up with Android 5.0.1. Should I upgrade to Marshmallow? It is asking me to do so but I'm concerned that WiFi calling does not work as well in Marshmallow. Does anybody else have any experience with this? Thank you!

PS: If I decide not to upgrade, how the heck do I get rid of that notification?

 

[shovenose]

Well, as per my other thread with graphical glitches, i did try upgrading from 5 to 6 to resolve it, and it's a hardware issue, so it didn't help, but i'm returning the device. it did seem to work fine on wifi calling with marshmallow, so when i get the replacement, i will upgrade it as well.