Help with Ohms and Bi-Amping...

OK, I'm a NOOB, sorry...I have a Denon AVR-2808CI (110 Watts per ch) and am awaiting the arrival of my Monitor Audio Silver 5.1 system. All the MA speakers are rated at 6 Ohms; the fronts are RS6's (Sensitivity (1W@1M): 91 dB; Nominal Impedance: 6 Ohms; Power Handling (RMS): 120 W; Recm'd Amp (RMS): 40 - 120 W). The outputs on the back of the Denon are listed as 6 Ohms, except when using A + B (bi-amping) for the fronts, which says 8 Ohms. I asked Denon about this and the reply was that bi-amping 6 Ohm speakers may cause the unit to shut-down and/or damage it. I know the Denon guy must practice CYA in case an issue arises from advise he has given, so I was hoping to get another opinion or two, with a bit more objectivity. I don't plan on balls out cranking them, as I live in a townhouse. Does this Ohm issue really matter?