harsh tweeters are usually a result of phase interference due to reflections/diffraction from placement/aiming, and phase interference/acoustic phase as a result of the combination of tweeter/woofer at crossover frequencies.
factory tweeter locations are usually poor, and how the tweeter is mounted or interfaces with the factory grills makes a difference. the wavelengths being reproduced are small, and affected by surrounding surfaces/mounting.
the tweeters are separate from the woofers, and the crossover point is different from factory - acoustic phase plays a role here.
companies like Boston Acoustics don't make harsh sounding tweeters, but they test them in ideal conditions. i've taken tweeters i thought were harsh and put them in spheres and had them sound amazing. diffraction is real. i've changed crossover points and slopes and solved harsh sounding highs.
additionally, you could be hearing distortion in the form of harmonics. as you turn up the volume the amplifier distortion increases. as distortion increases, harmonics are introduced. tweeters suffer the most from increased distortion because of harmonics. when tweeters are blown, it's usually the result of an increase in delivered power in the form of harmonics from clipping.
my point is, replacing the tweeters with different models in the same location with the same amplification is not a likely solution to your problem.
acoustic phase is describing the signal from the speakers arriving at your ears - this is more important than electrical phase since acoustic phase involves the listening position. you need to consider that the tweeter signal needs to be in acoustic phase with the woofer signal or it will sound harsh. you'll think it's just the tweeters, but it's commonly the combination of the tweeter and woofer (since they crossover slopes are generally shallow). swapping polarity on the tweeter may or may not solve the problem based on the woofer separation and crossover point/slope.
you consider the acoustic centers of the drivers, then think that the path lengths traveled are different. then factor in specular reflections, and you have multiple arrival times. at high frequencies, those arrival times can result in constructive and destructive interference which sounds harsh.
the dome material matters much less than the placement. silk can sound "harsh" with poor placement and metal can sound "smooth" with proper placement.
