I have have just changed the original demons on my GT at 4,800 miles.
I have never felt they were particularly suited to the GT, ok on the twisties but lacking feel and horrible tramlining around town.
I replaced them with Avon AM 26's
Early days, but around town they are a revelation - no tramlining, it's like a new bike!
Feels ok on the twisties too & for me offers more feel.
Weather here is atrocious at the moment so will update when I get a chance to put some more miles on them