Oh, I think I finally get it. Sven doesn't recommend Dark Urge as a first playthrough because he assumes most people will want to play it because of the insane murderous psychopath route. I guess if you kill most of your companions, you're really missing out on a big part of the story, so it makes perfect sense. But if you don't plan on giving in to darkness, then Urge is definitely a better option than Tav, especially because of the extra content.
I understood it as "don't play that one first, it makes more fun when you see how it diverges from a more normal playthrough". Basically, Tav gives you the baseline experience, Origin characters give you specific backgrounds for your companions and Dark Urge has a diverging path. If you play an Origin before Tav, you kinda know how the Origin Character thinks.
If you play Dark Urge first you do not know how their path diverges and is different.
If you have the Tav story or Urge story as base doesn't really matter. Unless you consider the Tav story to be boring and a clear downgrade compared to urge.
