Quiet mode in 5D3 and D800?

For those who own both the 5D3 and D800 bodies:

I am wondering how the 5D3 silent mode compares to the D800's quiet mode. Is it a lot quieter than the D800? Is it quiet enough that you can use it theatrical performances without affecting the audiences around you?

Liveview mode don't count because I never use it. Thanks.