Hi Mike.
I have no experience on the Heidanau’s or the Sava’s that Nick has used this year so I will leave comments on their performance to others.
I do have experience of racing on Avon’s, Michelin’s and Dunlop’s. Both the Avon’s and Michelin’s griped well but tended to let go without warning, the better of the two being the Avon’s. Having raced on both the 18” KR825’s and 17”KR364’s Dunlop’s I consider them both superior to the Avon’s because they don’t let go without warning but tend to slide controllably. The KR364’s I have raced on have used the front tyre on the back as well as on the front so I can’t comment on the 115/50 rear. But I consider the 17” KR364’s better than the 18” KR825’s because the KR364’s have better grip at full lean and also give better feed back when they are about to go into a slide, also better control in the slide.
Mick.