I've had my 7D Mk II for about a month now. During that time I've shot 20,000 images. 15,000 of them were shot last week inside a dimly lit theatre. I'm pretty impressed with it so far. I bought it to replace a 1D Mk III which developed a fault and is no longer economical to repair. I must say I was hesitant to go back to the APS-C format, but this is quite a capable camera. I did have to stop using my "go to" lens for action shots in the Sigma 120-300 F2.8 after getting some very soft images in the theatre. I put my 70-200L back on and all was good. I found the performance at ISO 12800 was less than satisfactory, but ISO 6400 and 8000 was quite good. I didn't use my 5D Mk III inside the theatre as it did not have the required burst rate. I shot RAW and Large Fine JPEG to different cards and the 7D just kept shooting at 10fps, hardly ever hitting the buffer. I didn't get any of the colour banding noise of the 5D either, but lighting was different this year to last year when I used the 5D.
Shutter noise was low even though I didn't use "silent" mode. I'll post some selected shots when I get a chance, but I'll have to be choosey as they are of young girls in leotards and tutus.