When you hack a spectre, you get +1 points in attrition, the same as if you killed it. In addition, spectres tend to come in groups of 3 or 4, and if you hack one of them, you get the entire group. Often this will be +3 points, which is a decent reward.
It or they will then follow you around to the best of their ability (note: they can jump, it is just slow). The spectre also has an updated nameplate referencing the player who hacked it.
If the enemy kills one of your spectres they will then get +1.
While this arguably negates the gains of your original +1, it doesn't immediately negate any of the benefits.
- spectre armies are cool, they fight for you
- you have a spotter
- you have cover
- you have an escort
- +1 for hacking them
- anything they kill is more points for your score
- they will meet up with you after respawn
- you have something that shoots without considering tactics right next to you (they will shoot at at titan with their Volt for example, giving away your position)
- there is a trail of AI with your name on it following you
- the other team now has an extra set of npc's to dispatch for points
- takes time to hack
Is it recommended? It just depends on your gameplay. While hacking a spectre may cause an easy target, at that point in the match there are already many spectres as targets anyway. There is no detrimental aspect of hacking a spectre though.
Overall, it is just a fun aspect of the game. If you want to hack them, then do it. However, due to the time required of doing this, I have found that it can slow down your own personal score in the match if you attempt to seek them out. That said, it is still fun to make a spectre army, which is the point of the game anyway, right? :)