I might add here that flamenco players often like EXTRA-high tension strings. Since the strings don't move as much when you hit them, its a little better for playing fast. You can also get away with a slightly lower action. If you're playing nylon with a pick (some jazz players do this) I think extra-high tension is a good way to go.
I've got a set of D'Addario extra high tension on my main practice guitar now. Put them on there basically on a whim just to try. I was actually a little scared to try, but it didn't take very long to get used to them. Yes, they are "extra" high tension, and you can feel the difference, but in truth they're not THAT much harder than "hard" which aren't that much harder than normal. You're still dealing with way less tension than high tension electric guitar or acoustic guitar steel strings.
Now that I've had them on there for two months, I see why people like them. In addition to above, I find tuning stability is a little better, too. On the other hand (pun intended) it is a little more work for the left hand, particularly in holding down barres. I'm going to be stepping back down to hard tension for my next string change.
My suggestion for anyone asking this question is just to try different types. This is largely a question of personal preference and you'll never really know what you like or dislike and why unless you try. Its not like you're "marrying" a string. . . .you can "fool around" with a given tension set for a few months then "dump it" for something else. If you REALLY hate a given set you can always change it out.