I've only seen 1 boxer on my side (alliance) in Vindication BG (AV). I've probably had 20 tells of people who box but aren't on their boxing acct. I've seen a horde boxer on Gorefiend though - he had a PvE setup with like a warrior, mage, lock, priest etc... I rolled him when he was going after spirit towers - I almost felt bed since it's hard to stand up to 5 shamans with a pve group.