YES i broke my angle without nerfs on my friends yfz , then i rode the warrior with nerfs and believe me i have not broken my angle agian but had a lot of close calls on the yfz just saying my opinion
If you do normal trail riding and dont ride very hard, you dont need them. If you are like me or most other people, you like to ride hard all the time. So chances are, like dirtyblaster said, you are going to want them.
Yeah i agree that if you dont want to lose your foot then get them they will save you a lot of pain. I also agree that it makes your quad look alot better in the end.