Bryston - Stereo or Monoblock

To monoblock or not to monoblock.....that is the question.  I know some prefer the sound of a single amp running in stereo while others see the virtues of running monoblock amplifiers.  From what I can ascertain it would seem the primary benefit (assuming you can get the same power per channel running a single amp) is the benefit of shorter speaker cables.  

I have monoblock Shitt Vidars now running a pair of magnepan 1.7's.  It's sounds great.   I'm thinking of upgrading the speakers to either 3.7's or really taking the plunge and going directly to the 20.7's.  I've been told the same amp can run all three just as effectively (if you have an amp that can effectively run the 1.7's then they will run the 20.7's) but thinking of upgrading here as well.  Mainly Bryston.  Question is whether I should go with a monoblock configuration running 900W into 4 ohms or buying a larger single amp that has the same power output per channel?  

Appreciate your thoughts & insight.