I would lay money on it, that if your speakers didn’t need those extra watts, you’d be saying one stereo sounds better that two bridged, regardless of the cost saving.Perhaps.
But you did say that "distortion goes up" with bridged amps - however this is not the case with the AHB2 in bridged mono, nor into lower impedances in stereo mode for that matter. So in that respect it is a bit different to most conventional power amps.