As the "equipment manager" for my son, I prefer the XS. The LS2 is fine, but doing a "hot swap" is a more involved process. Just the other day, during pre-game warm-up, son was struggling and could tell his edges weren't right. Came off and I swapped his blades in probably 90 seconds with the XS holder. Didn't miss a shift. With his LS2s, that process would have taken much longer and required the tool, instead of just my two hands.
Haven't noticed any difference in the hold each provides to the blade. Now, granted this is our first year on the XS and our previous skates with LS2 were outgrown in a season, probably not enough time to significantly loosen the trigger mechanism up.
As for @boo10 comment on mechanical lock, the benefit to me is that XS is a manually manipulated lock. You can feel when it is loose and you can adjust it or know you have to replace it. With the LS2, you pull the trigger, listen for the click and hope for the best. No way to adjust or manipulate outside of trying to pop-out and re-install if you aren't getting proper engagement.