This entire argument to DBL XP or not to DBL XP was made moot a while back and for several reasons.
The game is 18yo.
The game, with the addition of Ourobous can be played in any order. So people who prefer to skip content and play out of order will be able to continue to do so. You will not have more people playing the game at the same rate.
The game with the addition of the difficulty slider can be played at any speed. So people will continue making Uber toons and setting the slider at its most difficult settings. Instead of having the ability to have a toon 1 to 50 in a day, the removal of DBL XP will make it 1 to 50 in two days.
Im convinced that people who complain about DBL XP and it’s use in game fail to see the larger picture. Even with the removal of DBL XP two things will nevertheless persist. One, people will continue to play the game out of order. And two, people will continue to level faster than them. DBL XP is not the imbalancing monster they make it out to be. They just fail to see their problem is not the DBL XP, but their problem is with multiple aspects of the game. These aspects will not be changed in this version of CoH.