Based on what we know, I’ve put some stats together.
Haven’t looked at the back braces yet, only rings and weapons.
Added all the stats from the rings (including the infusion), the new (basic) rings provide 247 in bonuses.
Adding together stats on an average exotic ring and gem, they add 227 in bonuses.
Adding together the stat on an average rare ring and gem, they add 191 in bonuses.
Meaning, the jump from exotic -> ascended is 8%, and the jump from rare -> exotic is 16%.
Weapons yield similar results, but rare -> exotic is 12% instead.
Infusions add 5 agony resist and 5 of a stat, they might be increased though, as they are only fine right now.
EDIT: Looking at the back brace, they would be 8% without the infusion slot, but the small stat bonuses on them inflates it to 15%.