There is something wrong with my estimate as well. I estimated that my 115 mag spread across 34 UTXOs was worth 3910 GRC of stake weight. This accounted for ~7.8% of my total weight so I shouldn't see a significant drop when disabling PoR staking. However, my tests showed that my stake rate halved. Granted, my tests were only done over a few days so they should maybe be taken with a grain of salt.