this is over simplifying a bit, but look at the xm-l figures here
1 xm-l at 3A = 881 lumen
3 xml at 1A each = 11 76 lumen
or
881 lumen with 1xml takes 3A
~881 lumen with 3xml takes 2.2A
ie 25% more run time
in addition, I have little need for several hundred meters of throw (if it also has spill). so, cramming them together with little reflectors is a benefit for me, instead of 4 larger reflectors.