There is a fair amount of difference between hexing and curses. Hexing is "low level" but actually takes a lot more effort. A curse is actually less effort and less emotional baggage tied into it, but you have to have a bit of schooling to do properly.
Hexing can be as simple as as energy work where you ball all your feelings up into a single point of energy and release it so that karma will be turned on to that person faster than otherwise might happen.
Is it maybe a matter of how its done? if its a matter of speeding up someones karma (to come back and teach them a lesson) its still "natural" you are just hurrying things a bit right? so would that still be "wrong"?
But cursing can be a matter of attaching something malevolent to someone or even an object they own or that you give to them, that does bring a mindless, unmeasured harm, and can be final in its effect.
Either way, you are not the one who determines what comes back onto the person. One is more "low level" and measured, you might even say more "just", but the other is more final and drastic (though that depends on what you are acutally cursing, the person or an object)? So does that make one better because it is not as bad? or because it uses the karma that person themselves created?
I wouldn't hex someone jsut cause they cut me off in traffic, or pissed me off (tempting though that is

). They have to do some major harm and no I'm not referring to the friend who just had his ex accuse him of molesting her daughter. There are some people I'd love to hex (like politicians) that are "hands off" cause I know I'm not supposed to. Much as I hate it (especially Steven Harper) there are some things that are supposed to be and I can usually tell the difference.
On the personal side of things, hexing can acutally be a a release of these hurt feelings. It can be really cathartic. Whereas cursing doesn't help you deal with the feelings beyond the fact that the person might now be dead and so they aren't still around pissing you off, or they might be in pain and otherwise growing as a person through this present struggle and therefore more/less likely to care about whether you are an annoyance/threat or whatever to them.
the only way I've even seen a curse come back to someone is if the cursed person found someone who could release the curse so it rebounded back to the curser. But the chances of that happening now-a-days are so bloody remote... its not really a consideration.
but a hex really does involve karma, and there is not really any way for that to rebound onto a person... so where does that leave it?
PS thanks so much for all your input. I've had this question for some time and have come to no new conclusions. and now I'm going to be starting a new philosophy course that deals with ethics etc...