On my custom built 'Martin Dreadnought' style guitar, these strings retain their brightness significantly longer than most untreated strings I have used, in my opinion. Very balanced and loud, and I can afford to go a guage lighter than with some other prominent brands, which is a real bonus!
Really great feel - they seem a bit more bend-able when required.
I have tried various accoustic strings, but these are hard to beat.
Make sure you put an accute right-angle bend on the tuning peg to prevent the round core from slipping within the string. (Most modern strings have hex cores and are less fussy in this respect).
I think it is the 'old school' round core which gives the string its distinctive sound and feel.
Great guitars deserve great strings. Just off to find a great guitarist...