6 AGI = 0.24% Dodge
15 Defense Rating = 6.25 Defense Skill = 0.25% Block/Dodge/Parry/Miss = 1% to Uncrushable or 0.75% Pure Avoidence.
6 stats will get you 1/3 of the pure avoidence and 1/4 of block+avoidence that 15 Defense does. It will also give you a negligible amount of armor (agi), AP (str), crit, MP, Spell Crit, blah blah blah and 60 raw HP that CAN be modified by your built in Paladin bonuses such as talents and Kings. By memory (too lazy to do the math right now) that should put your HP bonus from 6 stats to 75 or 76.
150 HP is NOT modified by Sacred Duty, Combat Expertise, or Kings (since it gives you pure HP and not Stamina).
I would personally never even consider +6 stats. Even before 15 Defense was added it seemed like a gimmick to me compared to 150 HP. If 15 Defense had been available at the time, I would have used it straight through from level 70 to my first couple pieces of Tier 6 armor. Defense is something I can't seem to get rid of now, and I proudly don 150 HP.
Your mileage may vary though. You might see value in 6 stats.