The reason I am doing this is because I value achievement completion. However, there is a massive downside to this particular achievement in that, whenever you switch factions you lose all progression in your faction rank and you will have to leave your guild. Not only that, but you will have to wait 7 days before you can switch back to a faction you have left. That’s 7 days you can’t be in your actual guild.
The purpose of starting on the opposite faction is that I can do my 1,000 kills and then switch to my preferred faction without having truly lost anything important. I can do the kills, switch to my preferred faction immediately and start helping out my guild.
The benefit of trading them in a Blade And Soul Gold party is that you can resurrect the people much faster after you down them. This will speed up the entire process greatly.
In addition to the Double Agent achievement, every person in the group, after completing both sets, will have 2,000/10,000 player kills. This will not only allow them to purchase the veil that hides your name/guild at the misteye woods faction vendor after 1,000 faction kills, but will also give them 250 pierce from completing 1,000 kills.
There are also achievements for dying 1,000 times, rezzing people 1,000 times, and helping someone meditate 1,000 times. This will get you pretty far along in those achievements as well.
As far as making things “stupid and dull” I disagree. I just want to get this particular achievement out of the way so that I don’t have to suffer the negative effects of changing factions later.