I've been doing an apples to apples comparison on my gravel bike, swapped the r8000 nonclutched RD for the rx800 clutched RD. With the clutch off I'd guess the spring is 1.5x stronger than the r8000. How much that translates to watts in the exact same gear is hard to quantify but spinning on the stand there is some noticeable drag. When the clutch is on there isn't any noticeable additional drag except when shifting where the clutch resists pedalling for a split second. Will probably leave the clutch off for road riding and only turn the clutch on for gravel. Overall happier with the shimano rx800 compared to the sram force cx1 in terms of drag and performance FWIW 1x or 2x.