Brief PIREP. Well, I have only flown about 3 hrs on them now, but they are fantastic. Keep in mind, I am comparing them to my typical headset which was an entry level passive Sigtronics S-20 with Gel-Seals. Clamping - Very light, and hardly noticable for the typical 1 hr flights I have made with them so far. Looking forward to Windwood where I'll have them on longer for the flight. I do feel they clamped a little more than the DC X-11's I tried a few weeks ago, but not much. Could be that they just fit me better than the X-11's. Sound - Passive (ANR off) - these still block out a great deal of noise and seal up well, better passive than my S-20's. Turn on the ANR and Wow, this is cool technology,... Bluetooth - Easy connectivity to my iPhone, clear and easy to adjust volume. Haven't tried a call yet from in the plane. When I received them at work I called Gary and could hear his voice message in the headset, but he couldn't hear me when I thought I left a message. Apparently The Mic only works only when plugged into the intercom, unlike the Zulu's, where you can make a call from your office chair when you get them (AdamZ) Not an issue as I'll have them in the plane when I need to make the call, just an odd difference. Fit - For me, these fit great. The ajustable width on the headband allows me to get the width right so the earcups aren't tipped on way or the other and fit squarely against my head. Seems to be a good seal yet with my aviation sunglasses on, as they have a flat sided arm that slides in nicely and the earseal wraps easily over. Foggles though, don't fit up easily as they cause an opening in the earseal letting all the noise back in For now, I tip my foggles to rest on top of the earcups. I may try a set of JeppShades to see how they fit. The padded headband is nice. Case - The case is nice, and I'm glad it has the little pocket inside to organize the cord and control box/battery box. The On/Off button is sensitive, so I have to be sure I didn't accidently turn it on when packing it up. Very Happy with the Sierra!