In my experience, the MBLs are one of the most forgiving speakers with far less effects of walls. Since 101E MkIIs have 'subwoofers' that are conventional cone type, they behave similar to other subwoofers - liking to be placed near room boundaries. However, the mids and high drivers do like to be away from walls for better imaging like other conventional speakers... but far less detrimental if you can't placement them in ideal positions.
One of my 101Es are around both 4' away from the side walls but one is 8' away from the back wall and the other is less than 4' away. I still get pretty much balanced sound.