The website for JP Strings has full details of the range
The Thomastik-John Pearse Folk set is not very fully described in the website, which gives the impression it may be 'wound nylon' set similar to other classical strings which have a nylon core, wound with a fine plastic wrap, on the B and G and sometimes even on the top E. This gives a much brighter tone than plain nylon, without the rather 'dark' quality produced by the D'Addario Pro Arte Composite G string.
In fact the Thomastik-John Pearse set is really an alternative to a silk-n-steel set, with even lower tension, for putting steel strings on instruments designed for gut or nylon. The upper three strings are wrapped in a flat, clear nylon layer which makes them slightly easier on the fingertip than a very light gauge wire would be. Consequently they are very easy to play. The light tension, however, makes them difficult to control in terms of precision timing at high speed, and the open strings tend to resonate a great deal as very little energy is needed to shift them.
At $20.50 a set, these strings are far from cheap, and the bass strings are no more durable than any other classical set.
I have put two MP3 files here.
The first is a very short (20 seconds) couple of passes with Thomastik-JP strings on my Lowden S25J nylon string jazz model using a banjo style clawhammer thumb and first finger picking style. You can hear the tone of the 2nd and 3rd strings, mainly, and at the end I have put a few notes in on the top E string which does sound entirely different. The bass three strings are used but you can tell they are much the same as any other set.
The second is a much, much longer experiment in using the tones of the strings, concentrating mainly on the unique sound of the G string. It's 3Mb and about 3 minutes long. This is not a specific tune, or indeed anything - it's just Celtic references assembled on the fly to showcase the incredibly dark, almost sitar-like tones created on this cedar top guitar by these strings.
I do not think I will string the instrument this way again, because in doing so I lose my nylon string guitar and gain something entirely different. However, if I was a recording artist and had access to several guitars, I would unhesitatingly keep one strung this way just to be able to use this distinctive sound.