Now I have tested and compared. I was lucky as hell! I have a pair of QLN ONE speakers. The Dayton ND25FW-4 fit EXACTLY in the hole where the existing SEAS 25TNF/T tweeter sits. I mean exactly, edge to edge with the baffle. How is that even possible? Screw holes in the same place too.
I know you can't (or shouldn't) change tweeters at random. There is a lot that has to be right then with crossover, sensitivity tweeter vs bass/mid, Ohms that can differ, different frequency response on/off axes and so on. Nevertheless, since I could do it so easily, switch that is, I did. It worked surprisingly well with the Dayton ND25FW-4.A nice little tweeter that Dayton ND25FW-4.
With a little miscellaneous fixing, maybe with miniDSP and one amp that power bass/mid and another amp for the tweeter as well as trickery with finding a sensible crossover point (plus measurement with a microphone then) that QLN ONE with Dayton ND25FW-4 could perhaps become a really good speaker.

That IF it weren't for the fact that they have hopelessly bad, almost non existent, bass. Almost as if there was something wrong with them. When I turned the tone controls and turned on the loudness with the Luxor 7082A amplifier I tested with, they sounded okay. Those QLN ONEs are suitable to be placed in corners, or placed directly against the rear wall for bass support, that's my guess.
I plugged in an XTZ Tune 4 speaker on one channel and the other a QLN ONE. I set all tone controls to neutral. Then turn the balance on the amplifier. Listened to one speaker then the other. QLN ONE didn't stand a chance. XTZ Tune 4 is much better. Much more homogenous speaker with sensible FR.
(XTZ Tune 4 is an active speaker with which I tested with the amplifier not installed).
I'm looking for some active/powered speakers that have a sub output, to use nearfield with a subwoofer which I already have. Came across these https://www.xtzsound.eu/product/tune-4?technical which seem to have pretty good specs on paper, 52hz -3 point for a 4 inch woofer seems really good, ...
audiosciencereview.com
Original tweeters in QLN ONE:
(data on those in the attached images)
Sorry for the blurry pictures:
No screws inserted in this picture. I sat in them later. BUT check edge to edge with the baffle.
The Luxor 7082A amplifier, with the tone controls set when I listen to the QLN ONE. Then they sound okay. Those QLN ONE probably require proper, serious EQ to be good.