TJ, my theory is more edges and holes in the Galfer rotors = less of a film of water between the pad and the disc, which I have read is the main cause of squeeling in the wet. Also Magura and Galfer (both of whom do very similar looking rotors) both advertise them as being quiet or noise free.
This is also why some suggest sintered pads are quieter in the wet, as there are more voids in the pad material for the water to displace into. I’m not so sure about that though, anecdotally sintered pads are apparently noisier.
I’m confident it’s not a contamination issue, it only happens in the wet and the brakes are quiet and powerful in the dry. Also the bike has barely been used enough to pick up contamination gradually, and I’ve barely washed or oiled it (and only use drip on Finish line on the chain) so I doubt I’ve caused any contamination.
Re: harmonics etc, wouldn’t a different style of rotor have different harmonics as it will flex/vibrate differently?
Worth a try anyway, the bike is basically unrideable in the wet as it is.