Good luck finding a new endo.
My philosophy regarding doctors is there's a large proportion of fools among them, there's a few great ones, and there's the rest. You need to try to figure out which type you have. Don't take it on trust that because they have qualifications they are competent, or that the medical profession will weed out the bad ones - it won't. I've had way to many bad experiences.
I'm not saying you current endo is bad, but there's always that possibility. I always double check my doctors at every opportunity to try and work it out. For example, asking questions that I already know the answer to, just to see what they say. Asking other doctors about the treatment so see what they say. I read the literature where possible to check, and to see if they are up to date.
Regarding implants they have been used for years by genetic women, and if they were seriously dangerous no one would be using them. Life is all about risk, and you need to judge whats acceptable. Is a small risk of dying from an implant worth the risk? Whats sufficiently small? To put it in perspective, you've probably got a 1% or so chance of dying in a car accident. I'm overweight, and that's a pretty serious risk. Not much drinking but only because I don't like it. Apparently taking estrogen is dangerous - it increases the risk of dying from various things, and so does taking testosterone. I'm quite sure I've got vastly more risk of dying sooner if I don't take it though.
If the doctor says something is risky but won't quantity it, he's projecting his personal beliefs onto my treatment. That's not acceptable.
Personally I really like implants, and if something goes bad, well, it was my choice and my responsibility.