Shadow Dance?Follow

So, I'm looking at leveling my rogue again (my laziness in running instances and buying new gear stopped me before, but BoA gear changes things a bit...), and I love the idea of subtlety. I'm not really interested in maximizing my dps while leveling, but I am the type who plans my endgame really early. That said, I've been looking at the tree and the idea of Shadow Dance intrigues me. So my question is pretty simple. I see a lot of people talk about HaT builds, but it seems like when people talk about subtlety it ends at HaT...is the bottom of the tree just not worth it? Or is it just that the other trees are more efficient at increasing dps? I am looking more at PvE, but I do recognize that shadowdance is the definition of a PvP ability (high burst potential occasionally). I'm just curious if people have tried it out much in parties? Also, is it that good in PvP, or is it just so-so?

On a side note, do you guys see dual-spec changing your style that much? I mean, now you can go more pure dps spec and have an off-spec for times when you think things might get dicey or you need CC. Do you plan on doing this, or sticking with your same spec and not even worrying about off-spec? Just curious....been trying to figure out also if it'll be worth throwing 1K on my rogue when he hits 40 to have the dual-spec option.