Proof of ranged attack boost: http://www.bluegartr.com/threads/115679-Sylvan-Caban-2-Testing
I just finished doing some quick testing in abyssea to determine the exact boost. I was able to cap my attack vs pachypodiums with atmas + berserk. My damage capped at 333 with bronze bullets and annihilator (99).
Gear:
Findings:
Caban + Legs + Feet = 333 (capped)
Caban + No Legs + Feet = 333 (capped)
Caban + No Legs + No Feet = 329-333 (not capped)
Tessera + Legs + Feet = 333 (capped)
Tessera + No Legs + Feet = 328-333 (not capped)
Tessera + No Legs + No Feet = 323-333 (not capped)
Dux body +1 + No Feet + No Legs = 315-324 (more obvious proof caban increases ranged attack)
Conclusions:
I haven't done any of the math calculations, but I can conclude that caban is adding a significant amount of damage. If you compare the Tessera with no legs, to the Caban with no legs and no feet, the ranges are almost exactly the same, with the Caban slightly ahead. Thus, Caban is increasing damage by an amount equivalent to 36+ ranged attack (tessera's ranged attack + scout's feet +2). I'll do the math later to figure out a possible %.