Trueborn are one of the units that have evolved with me as I continue to get more and more Dark Eldar games in. I have went through many iterations of Trueborn units, and they are truly a versatile unit that can be formed into many different list sytles.
While it is true that you needn't count on gaining pain tokens to be successful with Dark Eldar, it is true that you should be maximizing your gains by taking advantage of them. Regarding pain tokens, you do not gain one for destroying vehicles, and your own vehicles can gain a pain token. This is the primary reason that I subscribe to using infantry to kill infantry, and vehicles to kill vehicles with my dark eldar.
Trueborn are one of those units that can be maximized very easily into killing enemy infantry for minimal costs.
Now I have gone through using Blaster Trueborn, as well as Trueborn with dual Dark Lances. The issue with these units is exactly what I mentioned before, if possible I want vehicles killing vehicles and infantry killing infantry. Which is why I keep falling down to Splinter Cannon Trueborn.
Look at it this way. 56pts gives you three models with two splinter cannons. That equals 12 splinter cannon shots at 36" all for 56 points. Lets assume a 2000+ pt game, and thats 336pts for 72 Spltnr Cannon shots at 36". Six units of 3 trueborn.
I have had game after game with these small units, and they are the thorn in the side of many opponents. Even a single surviving Trueborn with a splinter cannon must be dealt with, after all, its 6 shots. In several of my last games, I have had 2-4 units of one trueborn with a splinter cannon ripping up infantry units all on their own. Its a small point investment for such a large gain.
Now I know a lot of you don't like spam, but I always tend to start with efficiency, and then adjust my lists as I see fit down the road. (the lists tend to unspam as the get refined).
While I am not going to talk a lot about the Venom here, you can see that units of trueborn are much more efficient at killing (and gaining pain tokens) than Venoms. Of course I generally still like to take a couple venoms, but I do not do venom spam. I want raiders.
So in list building when it comes down to my elite choices, I love fielding 3 or 6 trueborn units of 3. Drop them in some terrain, or behind an aegis defense line, and they are deadly. Of course you still need to counter balance that with your anti-tank weaponry, but with Ravagers and Raiders, or even flyers, Dark Eldar can handle their own.
Of course if your list is geared differently, do not forget some of the basics of Trueborn usage. They can take Haywire Grenades, dual Dark Lances, or even be geared for some close combat effectiveness. A Dracon is can be a huge boon to any fast moving unit with its large number (worthy of an HQ for many armies) of attacks. Trueborn should be considered for almost any list style, or there should be a good reason for them not to be there.