My experience is, you should always milk for as long as possible as a boxer.

Couple simple reasons. You're not as flexible and able to recover from mistakes as well as semi competent 5 man groups can. You're going to make mistakes, or you're going to be playing super conservative and much slower than you need to be.

With how hit/damage scales with levels, you can tank and kill a whole lot more greens which ultimately equates to a higher rate of XP.

Currently what I am doing is, I have my full team with ravagers, as well as a more level appropriate weapon. I hot swap between the weapons based on situation. Is this pull > 4 mobs? Ravagers out! Is this =< 4 mobs? Keep the higher DPS weapons out. Since I prefer to stick around when dungeons are blue/green and do BIG pulls kiting with piercing howl, I use my ravagers a lot.

Basically, the drop off in xp isn't so bad when you are able to increase the rate of killing + size of groups you kill.