I agree that silk's are far less hostile than metal tweeters. However, the crossover slope shouldn't make a bit of difference in the presentation of the tweeter. The crossover has everything to do with the integration of tweeter and the mid/bass driver. The tonality of the tweeter is inherent in it's design and materials and how loud it is in comparison to the loudness of that mid/bass driver (talking about relative efficiency here).
Enjoy,
Bob
Enjoy,
Bob