I know this thread is old, but I just wanted to pop in and share my own experience. Basically I think it's an unknown area for each person, there are so many different ways of administering local anaesthesia and so many different theories as to why it sometimes doesn't work and how changing how it is administered might make it work. Some people have never had local anaesthics work, but a lot seem to be like me where sometimes it has, sometimes it hasn't and you don't have enough details to work out why it has worked sometimes and others not. I had a local anaesthetic administered whilst under a general for relief of post surgical shoulder pain, which worked so well it numbed the bottom of my mouth making eating diffcult, I've also had it for injecting die into my hip joint to get it imaged and felt everything!
I've not had a caesarean, but was anaesthetised for one whilst they figured out if they needed to get my daughter out quickly or not, they didn't, but I'm pretty confident I wasn't numb enough for a caesarean - I could walk, I could feel my skin, though it did still have some effect as I couldn't feel any uterine pain from contractions, shame it was hurting in my back and pelvis. This was having had a spinal, where they inject the drugs straight in, one layer deeper than where they would usually place an epidural catheter and then having the epidural catheter placed, given the standard dose and a few top ups.
I suspect that a knowledgeable anaethetist should have enough techniques up his sleeve to get most EDSers numbed up enough, but they need to be open minded, doses may need to be much higher and topped up sooner. I think what is more important than knowing your options is to know that the anaesthetist is on your side and will not let the surgeon touch you until you are numbed up enough and will intervene if the situation changes, anaesthetic issues don't happen because they can't get you numb or knock you out, but because they don't believe that you aren't. So it's important to understand what you are expected to feel, tugging, pulling pressure etc. and for the caregivers to know you understand that and you aren't describing these sensations as pain. Try to have a birth partner who is prepared to be an advocate for you, they need to know that if you say you are in pain, or your body language suggests pain that it means you are in pain and if no one is doing anything, they need to step in and say they need to sort that out.
If I have another baby, it will almost certainly be an elective caesarean, even though I know that on the basic dose I didn't get numbed up enough, I would definitely want to try for regional anaethesia, as well as allowing you to be there for the birth, it's better for the baby too, even the short time they are in you whilst you are out impacts slightly on outcomes. Key things will be making sure both anaesthetist and surgeon understand that this is a concern and that trusting they won't operate with me in pain is far more important than how they anaethetise me. Also, as most don't allow the father to be present if a GA is used, based on the belief that the father is there for the mother, not for the birth of the baby, that they know that having my husband witness the birth is very important to me to help minimise risk of disassociation that is common when mothers are knocked out and have the baby brought to them later.