Hi Peter
From my understanding the whole limit is not the roles but the associated generated profiles. This comes back to the table storage for user access.
AGR_USERS tables has an entry person user/role/validity date (i.e SU01 Roles Tab). However, USR04 has a single entry per user with all of the profile listed in a single cell. Due to the size of an attribute, there is a limit of up to about 312 profiles.
I think this is based on 312 * 12 characters for profile length (3744 characters) => less than maximum field size (3750 - quick google search on field PROFs length). In addition, the role might have more than one generated profile (incremented due to size of the profile) so it's not quite number of roles determines the limit.
Anyway, I don't know if it's changed but my recommendation would be to check if the table definition of the USR04 has changed and splits out user and profile?
Alternatively, assign 313 roles to a user with generated profile and see what happens?
Regards
Colleen
P.s which release? Could the comment be related to HANA platform possibly not needing to load buffer this way? (speculation here on my part).