Each of the drivers chosen has good response characteristics and controlled cones. None has annoying breakup mode resonance or anything like that, and each covers the range, so response is nice. Also, since the range is the same, intermodulation isn't a function of drivers. The main differences between them are in their harmonic distortion and their general build construction.

When making improvements, I prefer upgrading from the bottom up. Where harmonic distortion is concerned, it makes sense. The harmonics generated from woofers tend to be in the midrange and maybe that's why it is most noticeable to me. Harmonics from midrange drivers are shifted up into the overtone or treble region, which is another area that is important. But I think woofer harmonics are more noticeable. Harmonics from tweeters are shifted up very high in frequency, so while I think distortion performance is important there too, I think it's the least noticeable.