The specs are misleading pwx naturally rolls off at 2.5khz. It plays up to 5khz but it dies out a lot before then hence why i said its more of a midbass oriented driver that needs a tweeter that can play low or it should be in a 3 way active as a dedicated midbass while a dedicated midrange takes care of the upper vocals. In a well treated, deadened and enclosed door, can play lower than 50hz easy.
Difference between super tweets and silk domes is one sounds like pure garbage and requires a lot of work to get it remotely listenable without your ears bleeding and one actually sounds like how a tweet should sound, plays everything smoother along with playing a lot lower cleanly than what a super tweet can play.
super tweeters cant play low, they have super harsh peaks at 5khz to 8khz mainly all the SSSS and SHHH sounds ripping through your ears making you cry for mom. Horribly nasty. I would not recommend running super tweets unless you completely know how to properly SQ tune and found perfect off axis tweeter positioning and fabricating a proper tweeter enclosure in its respected place. Its not something you throw on an amp and set gains and expect it to sound good. Not even a good EQ can help you here. Its doable but i dont recommend an SQL newbie to run super tweets. Unless you like tapping people out with sh*t garbage sounding highs then go for it.