Seperate power amp.

Right now I am running a Yamaha avantage  2050 with Martin Logan esl, 2 dynamo 700, motion 8 and 2 psb imagine mini for my rears. I started out with an Emotiva basX 300 just to power the fronts but now decided to upgrade to the Emotiva XPS -3 Gen3 . A few questions I have though should I get the 2 channel xps instead of the 3 channel  and let my Yamaha power the center. I plan on letting the basX power the rear and the Yamaha handle the hights and atmos. The small savings that I would get from going to a 2 channel would just be reinvested into atmos speaker . 

Thank you for any advice . I'm still fairly new to the wonderful world of audioholics.