+1 on the vest style body armor for Off-Roading, I prefer it over individual pads as the mesh vest doesn't cut circulation to your hands nearly as much, although it does keep a lot of extra body heat in, bonus when its cold not so much in the summer. There is also a very direct correlation to the amount of protection / body armor you have on and your acceptable risk level, in my full dirtbike kit I am WAY more aggressive than when I have just a helmet and tee shirt on.
Mine is the Fox Racing Titan Sport Jacket, though several brands offer them and I imagine the protection level is all comparable
Not really ideal for use under modern name brand leathers that have all the padding built in already, perhaps if you had a lower end or custom leathers without built in elbow and shoulder padding, although unless they were already a little oversized the fit would be SUPER tight with that vest on
Also +1 on Revzilla for gear, they sell just about everything so its easy to compare and browse, good reviews and lots of useful questions about the products as well