no never needed one with the tracks i've used the 999 on although cadwell is an obvious exception.
i dont think its just a matter of replacing tyres because they are torn. if they are tearing its because they are not up to temperature and you are pushng them too hard. very easy to do with 140 bhp +
for me i would always now go for an sc1/2 combo with tyre warmers.
just to contradict myself though i might use the 999 at cadders without warmers!
i'm poor too.