Ref 110 using both 4 and 8 ohm taps?

I am using my Ref 110 with new B&W 805D's and read in a Ref 110 review that you can use the 8 ohm tap for the highs and the 4 ohm tap for the lows as my speakers are biwired. Anyone ever tried this? This may sound like a stupid question, but I always assumed you cannot use both taps at once.
This won't damage or confuse the amp in some way?
My 805D's have a nominal 8 ohm rating and an impedance drop to 4.7 ohms in the bass region around 200 htz, so thought it may make sense and give the amp a tigter grip on the bass region. I won't pretend to have a strong knowledge in this area, so if anyone has any input or first hand knowledge, it would be very appreciated.