I don't think G1/G2 are worth it.
Last month I used it on 2 windshields. One was brand new, the other I prepped with a PC7424 using Nanoskin's Autoscrub pad and Ceriglass with Carpro's Rayon glass polishing pad. G1/G2 is 100 times harder to apply (in the case of the prepped windshield, which...