I have waited a short while before posting my findings on these strings; usually I get excited and rave about a new discovery, but my enthusiasm wanes fairly quickly.
I have been delighted with the Argento strings. I splurged on the more expensive green label 99% set, which comes with two sets of trebles - one rectified, one clear.
I put the clear trebles on my Antonio Sanchez 1026 Cedar/Walnut, paired with the Argento basses. I have really enjoyed the results. I like some of the qualities of nylgut, and I like the clear, bell-like sounds of Mari trebles, and Aquila Cristallo, but the La Bella 202 nylons are my favourite so far. They seem to have a lot of the qualities of other strings, but stated more subtly - and the tension, not what I would call that high, seems just about right for me (although that may also have to do with the pieces am playing at the moment). I like the basses; they are not as over-ringy as I thought they might be, with some nuances of tone which I enjoy, and I do like the way they seem to work with the trebles. I am not convinced that the 'pure' silver approach is necessarily any better just because it's expensive or exclusive, but I will certainly keep going with them for now. I might compare with a set from the red label Argento.
I put the rectified trebles on my Asturias A80 cedar/rosewood, paired with Aquila Cristallo NT basses (the same basses as I think are found in the NT Alabastro, Zaffiro, and Rubino sets). The tension of the rectified trebles, which is slightly higher than with the clear 202 nylon, seems a happy match with NT Aquila. To me the sound is quite different, but quite delightful. In accord with another fairly recent post, the incidental noise of the trebles seems less obvious than with other rectified trebles, and the sound has a sort of authentic quality, made all the more striking by the almost 'dusty' feel to the strings on the right hand. The texture allows for a different right hand technique, using some more purchase to pull certain notes in a certain way - which I have been finding very satisfying. The Nylgut basses have a more throaty, bass quality to them, which also seems to have landed nicely next to these trebles.
So, while they were expensive, I effectively found new voices for two guitars with one set, and they are sufficiently different in quality for me to feel like I have two distinct instruments to hand. And for once, I don't seem to have found strings I like while thinking, 'Nice, but I think what would be even better...' - sometimes, I think, changing strings before I've had the best out of the current set up. I am happy with the way both guitars are sounding, and I'm looking forward to hearing the sound continuing to develop.