TPS/Quantum Screenwash is utterly pointless. It does absolutely nothing for performance aside from cool the IAT. I've done extensive logging and testing myself over the last few months.... It's not that i don't trust Niki, but i like to try/figure things out for myself. Niki has been widely publicising this for months as he probably sees it fairly frequently.
I'm currently running a 60:40 mix with de-ionised water and it is so much better. So much in fact that i am able to turn the timing up another '2' on the Revo software which is usually reserved for 100+ Octane race fuel. I'm running a considerable amount of timing now with no CF (timing pull) at all in the higher rpm, with only a tiny bit at lower rpm before the WMI activates.
Given how cheap the Meth and de-ionised water is, it's a no brainer.