I had a CVS which is practically the same, but instead of taking amniotic fluid, they took tissue from the placenta.
Whether you have the test or not depends on what your outcome will be dependent on the results. If you feel that you couldn't cope with a child with special needs or whether you just are the sort of person who just needs to prepare for that sort of news. I am the second type of person, and I actually found out that my baby does have downs syndrome. I couldn't terminate, but I feel lucky in some ways to be so prepared for my special little girl to be born.
The choice does have to be your own, and know that hospitals are very experienced with doing this procedure. It is slightly uncomfortable, and you do have to rest up afterwards.
I chose to go privately and went to Harley street in London to have my procedure done, as there was a slightly lower risk of mc there, but that was because of my history of mc (2 in the last year!) an I couldn't go through that again. Feel free to ask me any questions if you need to. Good luck with your choice, and just know that even if the outcome isn't that your baby has the regular 46 chromosomes - your baby is still your baby and there is light at the end of the tunnel! Xxxx