Their damage is comparable. Most people that go Spec Jur, go vit build. I asked a friend, and they said they haven't seen it proc very often but if that's not the case, they would go with Jur [3]. They also said a Spec Jur has more resale value than a normal Jur. Some good weapons to use are +10 DDPT (2x Doppel, Phreeoni, Turtle General) Main Gauche and +10 DDP Gladius (Both daggers, and are easier to sell when you plan to sell these). For basic, use a DD dagger to start, and then rest as you progress. And in terms of leveling, you'll need to pick leveling spots and get suitable racial/elemental/size weapons to be effective in them.
Edit: Note this. Eremes Guile doesn't work with daggers. Double attacks bypass crit so you won't crit enough with daggers. On Jur, yes. Katars double crit rate, so you would be able to crit enough with katars.