I don't think any of the 4in1s limit voltage, most of them are rated for 9.6 volts. What WILL happen is you risk burning up the components. The fact some people managed to run a 3 cell lipo on walkera 4in1's is a matter of sheer luck. I've had 4in1's burn out on 2 cell lipos or minor amp surges. Very few ESC's, if any, "limit" the voltage supplied to the motor. They have capacity ratings in which they are rated to operate properly without damage. Sometimes you can pump more juice through them without any negative effects. Sometimes you can't. Not all electronics are created equal. Even the same ESC's from the same company, some will work better (allow you to use higher voltage) while others will barely operate in their stock setting.

Honestly, avoid a 4in1. If you want a good setup, stick with all seperates, either buy a feda mixer and use a cheaper gyro, or just buy a heading hold gyro.

A mixer + gyro will probably cost you close to the same thing a semi-decent HH gyro like the align one would anyways. If you want the best performance, get a gy240 .