Furies, Why did it have to be Furies.
Who am I kidding, I had a former GF dressed as a Traditional Nun one Halloween and found that sexy. Especially when she threatened me with a ruler.
Where the bonuses *really* come in is in gear quality. Purple gear has significantly more bonus stats than blue (though you'll still end up with only 1-2% more damage/defense overall,) and the set bonuses from abyss dungeons are serious game changers.
Also, secondary stats (crit, swiftness) have very close to the same maximum values depending on quality, across all tiers. I've hovered very close the same amount of crit during my entire 50+ journey from 302 to 1325.
I hate to correct you Jo, but you're very incorrect. The +15 T2 will have about 80% of the defensive and primary offensive stats (attack power, str/dex/int) as +1 T3 (which you can get by forging your +15 T2 gear onto fresh T3.) I jumped from 45k hp to 77k hp, very significant.