I'd like to share my experience with these strings.
the first difference, IMHO, is the overall tension:
the Super Nylgut are softer, they have less tension (even if the A and G string have the same gauge) and it's more noticeable on the A string: usually most sets of strings have the A string with a lot of tension, making it harder to fret and a bit less "precise".
with the SN I've always found that the A string is easier to fret in every position.
the New Nylgut have more tension, the A string is a bit harder.
this thing is also related to the overall sound:
Super Nylgut have less volume and they "bark" less, they have a softer sound, less "harsh", and compared to the New Nylgut they are less "vintage", if the term is right.
just to explain: when I use the NN I feel that the ukulele has a fast attack on every note, and it sends me to those barky vintage ukulele sounds. It's a lot easier to get huge volume from them, like if only caressing the strings makes them scream.
I have a Mahimahi S3 (solid mahogany) that, after seven years of hard playing, with the NN screams as soon as I watch it
with the SN that fast attack is lost, the strings sing in a more open way, and while still keeping a vintage vibe, they aren't not so extreme, allowing softer dynamics easily, but due to the softer tension, they don't spark on the higher dynamics.
the softer tension, in my opinion, makes them less precise on the higher frets, because when fretting around the 9th or 12th fret, they slip under the fingers against the finger picking or the strumming, causing some slippery notes or some intonation problems.
up to the 5th/7th fret the Super Nylgut are wonderful, higher a bit less, but on a Soprano it's not that usual to go up to the 12th fret.
on the strumming side, the fast attack of the New Nylgut gives an "in the face" kind of sound, while the Super Nylgut gives a bassier sound.
for example: my sister has a Makala Dolphin, laminated, with a narrow body, and the factory Super Nylgut make it sings like a real instrument, and not a toy, with a full and deep sound.
on my solid mahogany ukuleles, with a deeper body and full sound on their own, the Super Nylgut tend to be muddy while strumming, but sweet sounding in finger picking.
so, on my sopranos I prefer the New Nylgut, I can hear better the "canto" notes even strumming hard, I can beat them harder and get a lot of sound with firmer strings.
if I was only looking for overall comfort, I'd pick the Super, but trying them head-to-head made me tend for the New.
PS: one thing to remember about nylguts is that they give the "real sound" after they are stabilized, in a couple of days. the first hours don't give you the actual sound, but once they are stabilized, here's the Aquila's scream.
how I've noticed that? simply because they clearly change the way they sound after a couple of days, when they don't go out of tune anymore.
in the last days in particular I tried different strings on my Kiwaya KTS4 bought a couple of months ago: it came with GHS black nylon strings, which I like, but I had this "compulsive-string-switching" after deciding, and I' noticed that when I switched back to the GHS, they always gave me the exact same sound, less stretching and fast tuning.
the Aquila (both New and Super) took more time to stretch while stringing, and a bit more time to stabilize the tuning. in the first two days they sounded dull and hard, but then, on the third day, wow!
bright and lively, driving the top like no other strings.
give them some time to settle in, and then they'll sound good, if you like that vintage sound.
PS: I'm waiting for them to settle in on my tenor. they are a bit harder than the GHS (same black nylon of the Kiwaya, a soprano/concert set), which on this ukulele I liked a lot, but the sound was too thin and guitar-like, I still prefer a punchier sound with more meat on the bass.
by far (I strung them yesterday) the sound is good, thick and hard, but the high strings are a bit dull. I'll check if they change.