I certainly don't need more power myself, though I do hear a benefit of having more power in reserve. The music emerges more relaxed, if you will.
I don't have a clear understanding of the topology of this amplifier yet, but it seems to me that bridging should give greater power supply noise reduction. By power supply noise, I mean anything entering, riding on or produced by the main output or any of the power rails---whether RFI/EMI picked up from god knows where, voltage variations emitted by the switching elements of the supply, variations created by current draws passing from a positive-impedance, dielectric absorption voltages from the ugly output and supply electrolytics, various resonances and instabilities---all of which exist dynamically in a complex state of constant movement and flux (simplistic sine-wave analyses don't come close to modeling this stuff). I'm speaking here of the entire gamut of AC existing on the power rails, which should be pure DC. Subject to limited feedback reduction, that noise will pass 1:1 through the Ncore FETs into your speakers into the air into your ear.
This is what I call power supply noise. It is always present and always affects any component operating where- and however. This noise, because largely dynamical, cannot be heard by placing one's ear at a tweeter. It's a kind of dynamical noise that veils the signal.
Subject to having a perfect DC supply that remains perfectly DC always (hence zero-impedance and absolutely linear, with perfectly ideal components), not to mention having a perfect amplifier, the only way to reduce this noise beyond reductions wrought by feedback or component quality is to have that noise cancel itself by operating differentially. It seems to me that bridging offers better differential noise cancellation than a mono amp can attain. One of the reasons this amp sounds so good stock is the considerable attention Bruno gave to differential operation. From what I can tell, the amp operates differentially from input to out.
Fwiw, bridging sounds quieter to me, more relaxed, less edgy in a kind of edge I associate with noise. I want to listen a little more, but merely my listening today has convinced me I will go with bridging using a single supply. I may someday hook up another supply to compare single- vs. dual-supply, but theoretically, one wants the very same noise signal on the + and – legs of the speaker terminal. That voltage will produce no signal in the driver. A single supply theoretically gives a closer approximation to the same noise signal on the output. Because the drivers are operated push-pull, that noise will cancel. What remains to produce sound is (more) the signal.
Also remember that current modulations in each of the supplies---the output, gate and buffer supplies---will produce noise as I've briefly described above that will intermodulate in complex ways with the operation of those supplies one to another. Reducing noise in any of the supplies will reduce that intermodulation, leading to cleaner DC rails for all active components in the amp.
