I have tried SRP on glass and the results were ok. If there is a line on the windows I would think this is more about insufficient buffing rather than a problem with SRP. Given the choice I would rather use something like Aquapel or Gtechniq G1 on my glass
Lowejackson- Thanks for the cudos Re my posts. That SRP + EGP combo was from an old suggestion by Richard Griot, back when he was selling Autoglym stuff in the days before his GG-branded products.