If you use a life battery in a high draw situation It will draw more voltage than what your cut off is set for , hence you would get shutdown condition , while still having a usable battery with amperage available .
A lipo batteries voltage does not vary during use while a lifes' battery does . So just like a nimh battery you can drive a vehicle till it becomes to slow to go .
Like I said in a transmitter it might not matter but would rather err on the side of caution using the proper settings of life battery , that being cut off is not used , low voltage detection yes , cut off no