From what I've seen and heard about the two, Dangerous would be the better one to get. I have Dangerous, and I love everything on it, but I think that it takes just too much effort to successfully learn the clipshift on Surfaced. I have the dvd, but I am just going to save it for when I am more experienced.
You shouldn't get Surfaced, go for Dangerous.
Tell me if this helps
I don't actually own Dangerous, but several people I know do, and I was was watching a really old vhs with Dai Vernon on it the other day and he was saying how he only liked to perfform the most difficult effects, he didn't want something everybody else could do.
To sum it up, if you are the typical, theory11/ellusionist fanboy, practice as little as possible but still want to perform a lot magician, go ahead and buy Dangerous, if you want to actually learn some advanced, difficult sleights that will advance your magic greatly if you put it to good use, buy Surfaced, the tricks are amazing. There's a reverse-elevator type trick on it as well, and it's pretty awesome. (lots of other stuff too)