I'm serious.
Light Armor will give you 22 PRR/MRR (82% damage from base 0) with 20 BAB, Heavy Armor will give you 56 PRR/MRR (64% damage from base 0). Evasion means you take 0% damage if you make your save but you'd take 50% damage regardless and then we apply the entire Heavy Armor MRR to reduce the damage even more.
With just the base 56 MRR at Level 20 you would take 32% damage from a Fireball on a successful save... then take Resists, Percentual Protection and additional PRR to the math...
We can now get 20% HP or 6 STR for just 13 AP in Sacred Defender and that's in addition to 25 PRR/MRR and other minor bonuses, but the 20% HP/6 STR is restricted to Medium and Heavy Armor. At that point in time you're taking 25% damage on a successful save, with just your armor and sacred defense on. No resists, nothing.
Seriously, there's no reason to use Light Armor anymore. I'll carry one in my inventory for when Evasion is especifically called out but otherwise I'll be going around in a Heavy Armor 99% of the time, in a Ranger.