Getting an SR to the same level as an R takes exactly the same amount of resources.
And yes, I have a tool that allows you to compare the effect of accessories on damage and endurance. Remember that ATK+ is only 3%, and since it's character attack it's only worth about 1.35% damage per buff. A full loadout of SSRs with 3x ATK+ each (9x total) will only increase damage by 24% (including the effects on base ATK rating), and only for that character. The benefits are much more meager than people tend to realize. Compare to affliction rate up, which can have substantial team-wide effects with even 3 buffs on a single character.