NB Bow/Bow DPS is higher than that of Warden BTW.
Bow Proc has higher tooltip than Lethal Arrow, Lethal Arrow needs the distance boost to outdamage bow procs, which is not always possible and also has a cast time. I personally get better results with Crushing Weapon than Lethal Arrow, as it allows more LAs for more bow procs in the same time.
NB higher DPS by a small margin comes down to the NB crit passives.
Bow Proc has higher tooltip than Lethal Arrow, Lethal Arrow needs the distance boost to outdamage bow procs, which is not always possible and also has a cast time. I personally get better results with Crushing Weapon than Lethal Arrow, as it allows more LAs for more bow procs in the same time.
NB higher DPS by a small margin comes down to the NB crit passives.