Super tweeters, are they worthwile?


Hello guys
I've been reading some infomation on the web about super tweeters and I've got curious.
First I didnt believe in subwoofers, I thought the would only add bass quantity to my system and then I got convinced and I tried one. Well, I couldnt believe how much it improved the 3D image, making it rock solid and so real. And I thought soundstage was mostly the tweeters job. 
Now I read some guys swear that super tweeters can also improve the soundstage, 3D image and bass!!  Well, If a sub can improve the mid and high frequencies, I think I can believe super tweeters could improve bass. 
First, I would like to now your experience with super tweeters, please only the ones who actually tried them. 
Second, if I listen all of my music streaming Tidal hifi (44.1 kHz), does this sample rate have ultrasonic infomation for the super tweeters to play? If not, does software or hardware (DAC) upsampling delivery it? 
Finally, wich super tweeters would you recomend under 1k the pair? I mean, ready to plug and play. I dont have the expertise, nor the time and patience to build crossovers, etc.
Just to mention, I live in a country where I dont have the chance to borrow them from a dealer with a trial period. I have to buy everything blindly. 
Thanks!! 

plga
I used to own the EnigmAcoustics Sopranino super-tweeter and liked what it did to my Magico Q3s. It’s not a good fit with my current M3s which are much more linear up to 40kHz and integrate better with the room. The issue with the Sopranino was integrating it, some experienced listeners always felt they could hear the transition, didn’t bother me but I heard an edge on some recordings.

I still wonder about trying one again and was taken with this review, the basic model in this series fits your budget and could be worth exploring
https://6moons.com/audioreview_articles/avantages2/
My Talon Khorus use super tweeters. Or is it super-duper? I forget. But I know they work, because when I play my test CD and it gets to 40,000 Hz I can put my ear right up to the superstar tweeter and can't hear anything. Since I can't hear anything that high I shouldn't be able to hear anything from the supernova tweeter, which I can't, and so I know its working.

Or it could be this is all mass confusion over the valid point that some sounds change so fast its the equivalent of ultra-sonic, which while quite different than an actual ultra-sonic frequency is a distinction a little too sophisticated for the average audiophile. Yeah. That's the one. Nailed it.
Ok guys, thanks for replying
What about sample rates??? 
If I play 44.1 kHz songs, they shouldnt have any ultra sonic frequencies, isn't it? 
Any thoughts about this subject??? 
Roberjeman you are the kid who called out all the royalties’ new and old clothes here. All psycho-acoustics. Unless we are looking at Lowther or Diatone that measurably roll off at 8k supertweeters just give confidence to the listener. Most people don’t realize "air" is at around 3-8k and not the upper extreme. In case of realistic in-room compensation of full range drivers, people often buy a superduper tweeter of some 98+dB efficiency and cross it -6dB per octave at 15k, not knowing that at one octave below: 7.5k, the tweeter still blasts out 92dB of "air" and that’s what they are hearing.