Sasuke mastered the Amaterasu with in 3 days and Itachi who had it more than 10 years couldn't master it like Sasuke and Sasuke used the full power of the MS in 3 days so what makes you think it will make any different for Sasuke now?
Sample, Susanoo was first an MS Technique and Itachi said once you get the EMS you will use the full power of the Uchihas now Sasuke has EMS and Madara has EMS too that's why he able to use Perfect Susanoo and please don't say it might be a Rinnegan Technique.