You'll get differing opinions with this question.
Here's some stuff to read through. Of course there are thousands more pages to be read also.
http://www.thegunzone.com/hague.html
http://en.wikipedia.org/wiki/Hollow_point
All I can offer is my personal opinion. I practice with fmj because it's cheaper. I use hp for defense. I have been lucky I guess, I have never owned a gun that would not reliably feed both fmj and hp.
I use hp for defense because I want the round to drop all it's energy into my target. I do not want to shoot through my target and possibly hurt anyone else. I think I have a better chance of stopping an attack with a hp than with a fmj.
That's why I don't get into the conversations about penatration and ss190/ss195 ammo. I doubt very seriously I'll ever have to shoot someone, and if I do, I doubt they will have armour. Am I positive of this? No. Are peoples faces armoured? No.
Looking at ballistic gel test pictures on the internet and reading atricles on wound cavities, with and without denim on the target, and also reading reports on real life shootings... I am very confident a 9mm, .40sw, 45acp hollow point will do what I need with the least risk of over penetration.
Are hollow points worth the money? To me they are, and I shoot mostly with fmj anyway. Do they do the job better? From what I have read, I think so. A bigger wound cavity, more energy absorbed by the target, less chance of hitting unintended objects, and just as good accuarcy.
TA