I've been reading up on intertype relations a bit recently and most of what I read seems to view these as moderately positive relations. Based on experience however I believe these to be quite shitty in spite of the types sharing the same quadra. I'll provide some simple, generalized examples so you can see what I mean:
SLE breaking the rules then being reprimanded by LSI.
EII criticizing IEE for teasing others in a somewhat offensive manner and IEE criticizing EII for over-seriousness.
LSE criticizing SLI for laziness and apathy and SLI in turn criticizing LSE for restlessness.
SEE criticizing ESI for living a turtled, sheltered, boxed up life and ESI criticizing SEE for playing power games and manipulating people.
ESE criticizing SEI for hoarding things too much to themselves and SEI criticizing ESE for possessive control in other's lives.
ILI criticizing the reckless risk taking of LIE and LIE criticizing ILI for passiveness.
LII criticizing ILE for inappropriateness and ILE criticizing LII for lack of spontaneity.
IEI criticizing EIE for disturbing the peace and traquility and EIE criticizing IEI for lack of involvement in the world.
There may be some explanations for this. Mirror relations are the only relations besides conflict where the types have opposing temperaments AND opposing styles of cognition. I saw somewhere that described Mirrors relations as direct mutual supervision and I would agree with this.