there a pretty good thread in the freeride section on this.
dainese is very good, costs a bomb, and is worth every cent.
but for $100 less you can get something like sinisalo armour. looks exactly the same, is also very good quality, and with the left over cash you can get a set of the new fox or axo hinged knee guards.
also don't forget that the dainese style armour was designed to go under leathers, so it isn't designed to be strong as such. always wear a jersey over it or it will rip.