I would recommend as a speaker builder, hobbiest to stay away from metal / plastic drivers if your ears are sensitive to harshness. The less harsh silk dome tweeters you can listen for hours. Some cone drivers can also be very smooth but can have picky resonaces not associated with metal. The cross over points are very important. Drivers have specific design ranges they operate best at. I have found a harsh sounding speaker ca be tamed down if the driver frequency limits are not pushed but made consevative within their design limits.
Your best option is to get your mask on and compare sound on the music you know as harsh on your system at a dealer showroom. My built speakers have aluminum dome midrange and compression titanium tweeter. I found a world of difference just changing the DAC from my network player to a Shiit Bifrost. Smoothed out to velvet voices. With metal drivers I enjoy dynamics and detail but have to be careful they dont bite on older badly EQd music.