I don't really know if this constitutes as a spoiler or not but anyway:

Yes, there is no reason to go higher than 567.

At some point you reach 80% damage reduction. That's the cap and it won't get higher regardless of your armor rating.

The armor cap does give you some freedom in pick which pieces to wear; while you're abusing blacksmithing.. :laugh:

That svcks when I can easily hit 1200 with heavy armour. Why would anyone use heavy armour if light armour can hit the max? Sigh... so sad.