I had DCDA twins. I did the research at the time and I think the EMCS rate was 34% (but please do your own research for MCDA and your consultant should be able to tell you the evidence based numbers). With those rates I thought it would be better to go for an ELCS. My consultant actually agreed & signed me off for an ELCS. (so contrary to slippery maiden's experience - but bear with me slippery!).
My twins happen to come early at 29 weeks. The SHO at the time did say that it was better for them to come vaginally. It's to do with fluid being pushed out of their lungs. But again, ask your consultant for the actual stats, because when I looked in to it (I love a good stat) it turned out that actually a small % of CS babies need help breathing afterwards and it all seemed quite minor. The other issue is that the babies pick up your good bacteria in their journey through the birth canal. However, nowadays you can ask for a swab of your vaginal bacteria to be swabbed over the babies (I know it sounds gross).
As it happens I went in to hospital with PROM and 2 live babies. After a couple of days I was transferred from labour ward to the antenatal ward. There I developed really bad, what I thought was, constipation. Turned out I was in labour. I hadn't done it before, I had no clue. Unfortunately the midwives thought I was moaning about constipation and I now fully understand the stories you read in the paper about ladies giving birth on the toilet! Contractions, as it turns out, are actually really hard on small prem babies … and my first born unfortunately didn't survive. For the second one I was rushed (the bed was bouncing off the walls) in to theatre and had an EMCS under GA. Not much fun I can tell you.
So, slipperymaiden, those vaginal births don't always work out that well for the neonates!
rebecca please don't let my story scare you. You might go to (almost) term which makes the situation v different and my story is quite uncommon of course. Although it has made me look at statistics very differently. Low probability, high impact. So I would opt for the safest way of delivery next time round. At the end of the day labour is only one day of their lives and ultimately the most important thing is they arrive safely.
Having said that, it is such a personal choice, (and I don't know anything about the MCDA twins). Even though it worked out really badly for me I am glad I had the experience of giving birth and found it an empowering experience. (I am sure that makes no sense at all, but there you go!)
Good luck xxx