Yeah, I see what you're saying Aranarth. I posted this guide mostly to give little hints as to what sort of things will work well against others. The thing is, not everyone has the same exact TAC list, despite what a lot of people tend to think. Some people like the Firestorm, some like the Fireknife, some go for railgun heavy lists, while others go for marker heavy lists. These pairings can go on and on. The point of the article was not exactly to say, take these units so you can beat the Dark Eldar, but give ideal counter units for the purposes of outlining exactly what you said below. As for tactics, I've found that these vary greatly based on the way the terrain is set up, and the player you are facing.
I don't think Broadsides are going down to DE, far from it. I just think that they are overkill against much of the army. This doesn't mean they don't have uses. One pair of Broadsides shooting at a Ravager will a. almost positively down it, and b. have paid for themselves (Victory Point wise) (almost) fully.
Honestly, against a Dark Eldar army, there are three types of tourny level armies, despite the diversity my post (deliberately) gave them. Warrior sniper squad spam (tons of Dark Lances), mobile Kabal (lots of Raiders and assault oriented units) and Wych Cult (either Webway Portal or Raider.) The point of an army like Dark Eldar is to be able to pull off fancy surprising tactics, and with their incredibly high average movement speed, catching you off guard is never too hard to do. The best route to victory against these guys is to think as many turns ahead as you possibly can.
You're right about the oxen squad- I am assuming a lot about them, and the situation they'd be in. I personally don't like them, though they definitely have their merits. I would go for Deathrains for anti-light tank if it came down between the two though, even if that is simply a personal opinion.
Now, onto the buried leading comment. TAC strategy, what to expect and how to react.
Plus- some new tactics that I find work wonders against any obnoxious DE players.
With the two main raider-mounted categories of armies (ignoring WWP Wych Cult and Sniper spam for now) you can expect to take a few casualties. Drones are marvelous in this case, as heavy weapons shots will be wasted against SD's invulnerable save, and gundrones will still be able to save key units when needed.
Moving away from unit choice, generally the Dark Eldar Strategy will work much like Mech Tau- focus fire/close combat on one portion of the enemy and overwhelm it. There is one fundamental difference though- they can and will charge into close combat with your units. So how does one deal with this? Exactly like you said. Essentially play to the Kau'yon stratagem here, leaving bait units (broadsides are an excellent example, to lure the raiders to stop, a point at which their weakest, and then shoot them to pieces, leaving his army stranded in a 'disadvantageous position.' If he does ignore them (which he might) then you can continue downing his most valuable transports (the ones carrying HQ etc) one to two at a time.
I would not try to do this though with a Webway Portal army. These armies tend to be 'mob' armies, closer to what 'high I orks' would look like. A ton of grunts with some heavy weapons and a few big monsters (Talos) If you do see that he will be playing with a webway portal, I would concentrate my forces and leave anything that is less mobile in reserve to bring on after he deploys the WWP. once the portal's been opened, the Dark Eldar Player has essentially committed himself to one location, and you can move to a more advantageous location. You can also be proactive on this part by deploying out of cover, giving you the widest firing lanes, limiting where the player will be able to hide long enough to drop his portal.
Anyways, thank you Aranarth. I appreciate your depth of thought that added considerably to the thread.
Have fun, and get us a few wins for the greater good