I have a Sierra headset and I also use a Zulu headset in my friends aircraft. Both are very comfortable even for hours on end. The Sierra has less noise reduction than the Zulu and is less expensive. I cannot stream Bluetooth music as on the Zulu, only telephone. You can input music from your tablet via a supplied mini-jack cable.
I have been using Lightspeed since the 20K, then 30-3G and now Sierra. There is a marked improvement in each generation. All problems I had (usually busted cables) were fixed free of charge (you pay one way postage to Germany).