Innocence - yes, exactly. I think the show actually does a really good job about not letting Neal off the hook easily for the things he does, but at the same time, he's got that innocence and sweetness acting as a sort of counterweight to his ability to charm and con people -- a natural way of putting the brakes on it. I get the impression that he really tries not to hurt people unless they've done something to deserve it, and he backpedals rapidly when it's pointed out that he actually has crossed a line. There are a number of episodes where he actively tries to "fix what he's broken" (like he said to Elizabeth at the end of season one).

I haven't seen enough of Patrick to get a good read on him, but just based on that one episode plus your meta and others' comments, my general impression is that he's like Neal with the brakes off - the same skill for using/conning people, but without the affectionate nature and tendency to get attached to people that makes Neal rein himself in. And that makes Patrick dangerous (and a little bit creepy). On the other hand, it makes him an interesting character, just in a different and perhaps, as you said, less endearing than Neal. But still complex and interesting.

(Oh, and I forgot to say this before, but your title is great. :D)