The question of 1.23 VSr vs 1.3 Vs for the minimum speed for Vref depends on the amendment standard of the rules at the time of applying for cert, plus any issue papers that may have shown up. It's got nothing to do, as has been stated, with any specific design feature (slats, FBW, whatever)
Note that this is only ONE of several minimum criteria for Vref. It doesn't always follow that Vref is set at this specific minimum