There was a deep dive by Reef Builders on the g6 par drop, and Jake (RIP) attributed it to par meters not picking up the UV spectrum of the new led layout (more UV spectrum). Jake also mentioned the potential to burn your corals if you don’t take that par discrepancy into account. I switched from Kessil ap9xs w/ led fill bars to g6 blues and I am absolutely happy.
With the g6 blues, I’m getting stronger and more varied colors (especially my blue and pink sps that just looked dead under the AP9X) even though my par meter (parwise) says I’ve dropped down from 250/300 par to 150. I’ll probably supplement my xr15s with an xr30 g6 blue in the future when the corals are ready for more light.