Tractor Beam (1)
Attack: Attack 1 ship. If this attack hits, the defender receives 1 tractor beam token. Then cancel all dice results. Range 1-3 Attack value 3.
Flechette Cannon (2)
Attack: Attack 1 Ship. If this attack hits, the defender suffers 1 damage and, if the defender is not stressed, it also received 1 stress token. Then cancel all dice results. Range 1-3 Attack value 3.
Ion Cannon (3)
Attack: Attack 1 ship. If this attack hits the target ship, the ship suffers 1 damage and receives 1 ion token. Then cancel all dice results. Range 1-3 Attack value 3.
NOTE: From what people have been able to decipher from the TIE Veterans posting, what the tractor beam token does is reduce the agility of the target by 1 until the end of the turn.
As of right now, these are the only cannons that work with the TIE/D title. The question is, which one is the best choice, and in what situation.
I will say up front, the best TIE Defender that this title works on is Colonel Vessery. The reason is that if his target has a Target Lock on him, Vessery will have the opportunity to earn, and spend, a target lock for each attack.
Tractor Beam.
This card is interesting. When coupled with a miniswarm, or a couple of other aces of equal or lower pilot skill, firing first with Vessery and hopefully applying the tractor token to make all future shots works well. Imagine having a 3 agility ship at 2 agility. Or a 1 agility ship at 0. Imagine cancelling the use of C-3P0. Imagine being able to make it so that the Y-Wing is unable to roll defense dice.
The catch is, when applied to Colonel Vessery, having his support ships in the squad able to take a target lock action at a lower pilot skill than Vessery so they can shoot AFTER he attempts to apply the token. For example, at 40 points you have have Vessery with a Stealth Device, Crack Shot, and the Tractor Beam. For 60 points you can have 4x Epsilon Pilots. Or a couple of Tempest Squadron Pilots and an Omega Squadron Pilot. Remove Crack Shot, add Veteran Instincts, and then add Juno and Maarek.
The point is, the Tractor Beam is useless in many builds, but with the right squad setup, being able to reduce the agility of your opponent for your remaining ships can be a game changer.
Flechette Cannon
If you only have two points and don't want to add a Tractor Beam, or your other ships have a higher pilot skill, this isn't a bad choice. Like the Ion Cannon it is able to deal 1 damage max. However, the stress token is applied ONLY if your opponent doesn't already have a stress token. That is the biggest weakness of the Flechette Cannon. You can either chose your target carefully to take advantage of that fact, or take a different cannon slot upgrade.
That being said, there is no need to have more than 1 TIE/D equipped with this cannon as the stress mechanic is wasted if you concentrate your fire on 1 target.
Ion Cannon
This is the current reigning king idea as far as cannons are concerned. Hit your opponent, deal that 1 damage, apply the Ion token, and know where your opponent will be next turn so you can repeat the process. Control, with a potential 4 damage (without factoring in crits) makes this a deadly choice.
However, there is a unique possibility. How about designing a squad that takes advantage of all three of these upgrade cards?
3x Delta Squadron Pilots
1 Tractor Beam
1 Flechette Cannon
1 Ion Cannon
3x Twin Ion Engine Mk. II
This presents a unique opportunity to be a total prick to your opponent. You fire the Tractor Beam ship first, hopefully reduce their agility, and then fire the other two ships. Having a ship stressed and then perform a white 1 forward keeps them in 1 location, and they are unable to perform any actions. However, the biggest drawback is the three very tempting targets at PS 1. A good enemy had a decent chance to kill one Defender before they can shoot......
Anyway, these are my thoughts on the TIE/D title and the cannons that work with it.