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. 

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lak3,559 posts
"Super tweeters can enhance the music including the sound stage as you noted in your opening questions. I own the Townsend Super Tweeters and I have found the results very positive however they seem to work better with some speakers verses other speakers, but they work, most likely depending upon the tweeters used in various speakers."

Ditto - I have them also... and... they do just that - they seem to add more presence, air and resolution.

Does anyone have experience comparing Supertweeters with SteinMusic Harmonizer, SR HFT, Bybee ARN? The listed products work perfectly in my system and I'm thinking about how to make an additional improvement.