It is usual to prescribe sequi HRT when you are still peri because your own hormones are still fluctuating and if you are put onto conti HRT, your cycle can break through and gives rise to a lot of irregular spotting and bleeding.
However those who use a Mirena are in effect on conti HRT anyway - becase this delivers a continuous dose of progestogen directly to the uterus. I presume the dose is so high that eventually the spotting and bleeding stop - and I think in many women who are not even peri-menopausal, their periods stop with a Mirena.
As far as I know there are no health disadvantages altough the research carried out into HRT ( the big study) found breast cancer rates to be higher in women using oestrogen and progestogen, so it could be argued that progestogens should be kept to a minimum.
However this research was flawed and with HRT consisting of equine oestrogens and a synthetic progestogen, and increasingly it is thought safer to use bio-identical HRT ie estradiol and progesterone - which is what I use (Estradot and Utrogestan), However I am still on a cycle even at 61.
Hurdity x