OK, please forgive my small ignorance, my comment on tyres was based on my experience with slightly larger bike, I.E. My Kawasaki 600RR which is powerful and heavy enough to work a tyre up to a good temperature.
My recently aquired MC21, I have just realised has some pretty old boots on it, 12 years old! Now I am not saying they don't work but in the recent test we have here on the Isle of Man (we only have one and that lasts for the life of the vehicle ....Yahoo...no MOT stresses here) The examiner noticed that small cracks were appearing in the grooves of the tread, which can't be good can it really?
So for the sake of a few hundred quid of tyres, verses even a slow speed slide off, I am going to replace them.

I spoke to the guys at my local tyre place, who are all bikers by the way,and they advised me that due to the power and weight of a sport 250 machine they would never (unless you are track daying it) really get that hot....or even warm and recommended that a set of the softest compound were the best option and his recommendation were Bridgestones.

Taking all that previous info into account, it is likely I am going to heed that, the problem at the moment is they don't have them in stock at the moment and Bridgestone are sending over container loads of tyres but not telling the stockist what is in them!
Such are the strange times we are living in.

Hope this helps you in your dilemma