In NYC that hideaway knife will probably be considered a "push dagger" and that's illegal to carry. The Boker Subcom isn't necessarily a bad idea but I'd rather have the largest blade I can legally carry. The NYC authorities love to label every knife a "weapon" or "dangerous knife" so what do you think is better for self-defense?
Technically, I believe that would be 4 inches. But try claiming that a knife just under 4 inches was not intended to be used as a weapon. The HAK utility style is not designed to be used or penetrate like a dagger. They have other, more sinister looking styles for that.

Emperor Bloomberg doesn't believe that the peasants can be trusted with sharp pointy things. So I don't really have the best answer for your question. However, that Vic Rescue Tool is very nice! I've been thinking about getting one for me, the wife and my dad for awhile. Nice idea.