In theory, there is no way that 2 drivers can cover a frequency range of 20Hz to 25000Hz as well as three drivers can. This of course assumes that everything else is equal such as, driver quality, proper crossover design, prober box design, etc.
If you build your own speakers, three ways also give you much more flexability to balance your sound to suit your particular taste. For example, I have adjustable L-pads on my mids and tweets so that I can bring the mids or highs up or down to achieve the sound that I desire. My woofs cover 20-500 Hz, my mids cover 500-5000Hz, and my tweets cover 5000-25000Hz
HG
If you build your own speakers, three ways also give you much more flexability to balance your sound to suit your particular taste. For example, I have adjustable L-pads on my mids and tweets so that I can bring the mids or highs up or down to achieve the sound that I desire. My woofs cover 20-500 Hz, my mids cover 500-5000Hz, and my tweets cover 5000-25000Hz
HG