@Snakebit.
And still you have yet to tell us these reasons and situations of yours.
On topic, Ive always been the aggro spy for my team so my partner can finish his job, and holding onto the merc for a bit and killing him is the way I usually go. The only situation I can see KOing the merc being more effective, is if the area he's been KO'd in is further from the next objective than the spawn point.
So my vote goes to KILL.
And still you have yet to tell us these reasons and situations of yours.
On topic, Ive always been the aggro spy for my team so my partner can finish his job, and holding onto the merc for a bit and killing him is the way I usually go. The only situation I can see KOing the merc being more effective, is if the area he's been KO'd in is further from the next objective than the spawn point.
So my vote goes to KILL.