Yup they are so pointless The Gp and wsb boys use em.......BSB use them and they are on pirelli rubber too,
But as I said earlier Horses for courses.
This is the info I had from Pirelli, Who as it goes Own Metzeler..
These are a starting point - you may prefer slightly higher or even slightly lower pressure depending on track temperature, riding style, suspension settings etc.
Tyre warmers - if you are going to use them, buy a good quality warmer with thermostatic control.
We recommend you use warmers for rain tyres as well as "drys".
Set temperature to 75 degrees C for 1 hour, then set pressures to:
Racetec's - 2.2bar (32psi) front and 2bar (29psi) rear
Rain Tyres - 2.3bar (33psi) front and 2.1bar (30psi) rear (I would recommend K1 compound front and rear for Rain tyres) - Only use rain tyres when there is standing water on the circuit. A drying line will destroy the tyres very quickly.
Tyre warmers aren't critical for either tyre, but you will get better performance throughout the life of the tyre if you do use them.
Metzeler Moto UK