Now you guy's been using this stuff for almost a year now is it still as good, as it first seemed
It all depends on what you put your lines through that will determine how long it lasts.
Example I used the sewers aid on my 50' set which is what I use the most, now I fly mostly on a grass field maybe 30 ft from the ocean tops and they have lasted quite well.
I would say its about time for another application that will maybe get me to early summer when I'll most likely replace the set anyhow.
I would think things like many twists from spins, flying on sand, water play would lessen the time between applications but I can say I'm a hard flyer and i beat my kites like I stole em and this stuff has lengthened my time before line replacement quite a bit.
I believe this set is 3 years old now and in the warmer months I do fly for hours daily so that is a good testament IMHO.
It's not a cure all or a miracle but for $6 for a small bottle it will prolong the life of your lines to make it worth the effort to apply.
Now that being said dirt, sand, sticks and cement park benches make for hell on a line set, dirty lines should be rinsed in fresh water because if it gets embedded that will shred your lines internally and there is no hope or fix for that.
Hope that helps somewhat.