Using GPIO0 and GPIO3 for I2C or I2S

[rohansingh]

I have a device with a large number of connections, and I'm trying to conserve as many GPIO pins as possible.

Would it be safe to use GPIO0 and GPIO3 with the I2C or I2S peripherals? I know these pins are needed by the serial bootloader, but they aren't needed once application code is running, right?

[rohansingh]

I've verified this experimentally and it does actually work. I'm able to detect an I2C device and read registers, even while using the serial monitor. I assume that sending bytes via the monitor could cause issues, but I don't plan to be doing that in my use case.