matthewclso:
Update March 25 2016: This trick is confirmed working nicely using three GY-521 breakouts along with an ESP8266 wifi/microcontroller (NodeMCU)."
A NodeMCU or other ESP8266 based board has a 3.3volt processor and runs on a 80 or 160Mhz clock speed.
So you're sure a Mega, clocked at 16Mhz, will run on 3.3volt.
Overclocking (which under-volting is) lowers reliability.
Seems like a desperate/dumb move to me.
Why not change it for a smaller 3.3volt high clockspeed board.
What are your other pin requirements, apart from the two I2C and 14 chip select lines.
Do you have the ability to remove the 2k2 resistors of 12 boards safely.
Leo..