Outofspace
Sogeking / Deeps
It isn't as bad as you think it is as long as you play the spec correctly (around gouge). But it is not the most braindead way to play a rogue at 19, i will give you that. It's a CC heavy spec with burst potencial against FC.
Double lifesteal or lifesteal + 15 agi (remember +15agi is not available atm) is actually really good against other rogues or warriors. That is why you play it. +5 damage is really good as well for your burst + backstab but won't help you with anything while kited / against another melee.
But at the end of the day, you play what you want to play. Like i said: for me, it's a nostalgia trip and i have countless hours of exp with this dagger rogue spec.
Well hey, everyone loves their own, as they say, so fair enough. You've got multiple things going on with your build, and sounds like some utility, which I get. This seems like a case where your two roles are at odds though - backstabbing a warrior who can hamstring you for instance is very difficult, would you want to SS with a Shadowfang in that case, even with your talents? And for burst I just can't get around not wanting +5 dmg mainhand for an Ambush/Backstab build.
I do get the nostalgia aspect though, I hope you get what you're after :]