Jein (Yes and no) I think. While new Miru is more loyal in bed than old Miru (old Miru was a full-blown slut in bed, but otherwise rather loyal if eccentric), she is not as adverse to sharing than it seems at first look. Yes, she was not really happy with the sharing discussion, but during it later on admits that it is not bad to trhink about it (since it is implied that she has a very high sex drive like old Miru and she does not want to cheat on the MC)
New Miru looks even better than old Miru, but I hope her new incarnation retains a lot of her old eccentricity. And considering their "playing tag" at home, it seems like it is the case.