Hi Plumblusher,
This must be a very worrying time for you, and it's not surprising you can't think straight.
I think there are a few things to take into consideration. I've had cvs twice, once with a 1:2 risk for T21 (it was T21) and once with a 1:1896 risk (it wasn't). Neither resulted in a miscarriage. I've never had a miscarriage, so that wasn't a particular fear for me, although I can understand why you would be scared to do anything that would increase your risk of miscarriage.
So, a few things -
Do you know what has led to your risk? As DontTell says, there are soft markers which indicate a higher risk of Down's syndrome: NT measurement, blood hormone levels (PAPP-A and beta HCG), blood flow between the liver and the heart (the flow through the ductus venosus), and the blood flow between the chambers of the heart. Not all hospitals use all these markers so you may not have all this information.
Some of these are more indicative than others eg 85% of babies with tricuspid regurgitation (the heart marker) also have Down's. Reverse flow through the ductus venosus also strongly suggests Down's. My first baby had both of these, which meant the likelihood of him having Down's has probably more than 50% even though his NT measurement was 1.5mm.
Secondly, your risk of Down's is currently 5%, and your stated miscarriage risk is 1%. So the likelihood of your baby having Down's is 5x the likelihood of you miscarrying from cvs. This will only change to 5% vs 0.67% with amnio. Only you know whether that's even of a difference to make the wait worthwhile.
Thirdly, as herecomesthesun says, the quoted rate for cvs (and amnio) is very out of date. In the hands of an experienced practitioner, it is much less. That's why I went ahead with a risk ratio of 1:1896 the second time even though most people will probably think I was a fool to do so. The rate also stems from research done in the 70s when they used to do cvs and amnio blind (no ultrasound, they just palpated the uterus and went in with the needle). I confirmed this with my consultant at the second cvs. So it is much safer now but they can't update the stats because no woman would agree to blind cvs when ultrasound is available! And, if you have cvs/amnio, many miscarriages that do occur, occur not because of the procedure, but because of the underlying health of the baby. But no-one would be able to pinpoint why the baby died, so it is attributed to the procedure because that is the unusual intervening event in the pregnancy.
I wish you all the best in making your decision - do come back and ask more questions if it helps, I know how awful it is to be faced with the prospect of something being wrong with your baby and wanting (and waiting) to know the truth.