Well think of it this way, you saw the amount of damage pein did right? And that wasn't even full nagato, and Edo nagato negged both Naruto and killer bee simultaneously and edos aren't even as strong as when they're alive, and only the original weilder can utilize the eyes to it's maximum power as you saw with Madara and he wasn't even using both eyes and you saw how destructive he was and sasuke is even above that so let that sink in. Not only that Sasuke retains his sharnningans abilities but they are boosted such as sharnningan genjutsu into rinnegan:genjutsu, so his perception skills are off the charts, when he adjusted to the eyes, everyone's name who wasn't Naruto was at his mercy and even then his eyes were still new so he couldn't use it to it's full potential. If Sasuke mastered the rinnegan that would put him on equal footing if not above Naruto.
The rinnegan does grant augmented strength via asura path and rinnegan enhanced susano, speed? Amenojikara is instant though and not even Naruto or madara could react in time to it, regeneration? Preta path much? Reflexes? Dude, Sasuke's rinnegan retains his sharnningan abilities to the highest degree meaning he can see a persons muscle tension even by the slightest movement and that's just basic three Tomoe, this is rinnegan we are talking about. Nit only that the rinnegan grants a plethora of other abilities, such as control over the soul via human path, chakra rods, gedo mazou, shinta tensei, tengai tensei (meteor), etc etc. The rinnegan grants Sasuke an infinite amount of potential. So RSM being equal seems about right.