Run&Gun
Veteran
I wouldn't want to do a 12 hour reality TV show shoot with an Amira on my shoulder all day (which I don't do that, because why would I want to do a 12 hour reality TV shoulder mounting with any camera?), but for say a narrative film, commercial, doc/corporate (interviews and short b-roll), etc., having a 30 lb camera on my shoulder for 5-10 minutes at a time typically isn't so tough. And if you can't handle that weight for a short period, probably good to either hit the gym or grow 20 years younger. More weight equals more inertia which means more organically stable footage without having to rely on artificial looking stabilization like optical IS, electronic IS, or a gimbal.
Yeah, I mostly use 280w batteries with my Amira which last around 4 hours (also powering a SmallHD and sometimes other accessories). Four hours is long enough for me to not be complaining, about the same amount of time I get with the larger BPA-60 batteries on my C300s.
Yeah, I wouldn't want to do a 12 hour reality show with anything, because I hate reality shows. But like you said, too, realistic shooting scenarios, you're fine with "heavy", well-balanced cameras. I did BTS on a commercial a few months ago and I used my Vari and there were plenty of times, especially during the first day, where I'd just leave the camera on my shoulder when not rolling, because it was balanced. There was no fighting it, even though it was 25lb+. I would have wasted more energy putting it down and picking it back up again. Obviously I'm not talking about an hour of down time, but if nothing was going on for a few minutes, it was fine sitting up there.