I just got a set of these, and put them on my bass today. Was hoping to have them for a gig last night, but didn't.
My impressions; I have been using a .040 set of ProSteels for a while now, so that's my comparison. I was looking for a brighter string, the way the old Rotosounds used to be.
These have a slightly rougher feel, which in my experience equates to them being brighter, and they are. I was a Rotosound Swingbass user back in the 70s. When Rotosound went back into the business, the strings changed, and the new ones are more polished on the surface, and nowhere near as bright as they used to be, which was a disappointment. And the low B was appalling and wouldn't play in tune up he neck.
So these remind me of the old Rotosounds, very bright and with that piano sound.
They don't seem more flexible to me at all, but I was using a lighter gauge, and hadn't used the .045 gauge ProSteels in at least 8 months. I had to tighten my truss rod a bit, but that's to be expected with the heavier gauge anyway. I'd like a lighter gauge set.
So far I like them. I was looking for something brighter than the ProSteels, and I got it.
As as always, D'Addario has the best low B string in the business. This one sounds a bit different from the ProSteels, but still vibrates well.