Complex sentence: The buffered versions also have faster output switching times, as the signal rise time of the buffered output stage is faster than that of an unbuffered device, however the overall propagation delay through the buffered versions is higher due to the additional circuitry.
Split into simpler sentences: The buffered versions also have faster output switching times, as the signal rise time of the buffered output stage is faster than that of an unbuffered device. However the overall propagation delay through the buffered versions is higher due to the additional circuitry.