OK, Red, not my field. Since leaving training the only babies I have delivered have been in the emergency room, by accident, or in stressful locations where no other medical assistance was available. With a consult with a midwife and a call to a friendly obstetrician, I found they were each profoundly disinterested. A review of literature showed up the original German studies and the small study in Australia, both oft-cited by Starnberg on the internet. Starnberg is the inventor/ marketer and that is worth noting.
The N. American and European approaches to episiotomy are generally different. The Americans, mostly, treat it as a normal part of childbirth and do the cut quite early and quite long. Europeans tend to wait until it becomes evident that it is necessary and make a smaller incision. There are many exceptions to this. The Americans tend to have fewer tears but long term results in damage to the genito-urinary system are not much different. The argument is that a clean cut, immediately treated is less likely to lead to infection or other damage; the other side, is not to cut when possible because any opening is a route for infection.
The epi is done to prevent tearing, mainly, of the perineum and does not usually result in cuts into muscle. It is possible that the anal sphincters are cut resulting in rectal incontinence or further surgery. If the suturing is not quite precise, the shape of the vaginal opening may be affected resulting in a degree of sexual dysfunction. The epi-No seems to be intended to gradually stretch the perineum giving it the elasticity (or looseness, I do not know which) to stretch over the baby's head.
Over the years, there have been many attempts at reducing the need - water birth, massage, heat and likely many more. The epi-No is a mechanical device that helps to train the woman for normal, spontaneous, vaginal birth. It is intuitively acceptable that this would work. Many things that re intuitively obvious, and work in small trials, in medicine do not work out in mass use.
I suggest you contact an obstetrical nurse at a nearby hospital and ask what doctors recommend the epi-No. That nurse, and the nurses who work with local obstetricians will be able to give you some insight and, even, introduce you to the doctors who may be recommending it.
I simply do not know enough to give a good response.
Posted: 30 Sep 19:20