Most recently I had Imperial trebles on the guitar. On paper these should be much higher in tension than the LaBella 2001. But if anything it seems the LaBella feels a bit tighter. The sound is different too, so it is difficult to be sure of this. But certainly higher in tension than D'Add J45s, again even if not so on paper. I read somewhere that LaBella measures tension for a 65.5 cm string length. I don't think measuring tensions with an 0.5 cm difference in length compared to a normal 65.0 cm scale length measurement, that I presume other manufacturers would use, explains the actual difference in how the strings feel.
So far I would characterize the string sound as more "pianistic" and less "lush" than lower tension strings. Very solid, seems good in volume too, good tone separation, not so easy for vibrato. But the tightness of treble strings seems to also change with how warm it is in my study (summer afternoons, any string tends to feel looser) and right now I mostly play during cool early mornings. That may be an entirely subjective effect, but something that seems to happen with all strings for me.
The basses are La Bella Argento Silver MT. So far I like those too.