IME people are too quick to blame single pivot calipers, they're not that much worse than dual pivots. It's not a difference between safe and lethal, at most they should make you think a little more about your braking.
On one of my bikes I have some early nineties single pivot Exage, on another there are late eighties Weinmann 570s. The Weinmanns were scaring me. As an experiment I swapped the front Weinmann onto the Exage equipped bike. Still not great but better. Interestingly the Exage didn't seem to perform as well when swapped onto the previously Weinmann equipped bike. Getting interested in the the variables I swapped the blocks between the two calipers. So I had the same blocks on rims on the two bikes as before. This time the Exage were just about as scary as the Weinmans had been. So a bit of fiddling showed that the block/rim combination was what made most of the difference. With the rim on the originally Weinmann equipped bike whatever brakes or blocks I used braking was less effective than with the other rim. Likewise the blocks fitted to the Weinmanns were not as effective as the blocks from the Exage. (Neither were OE blocks so don't read anything into that). However putting the poor rims with the poor blocks made for very little retardation at all.
So essentially we have three main variables. Firstly the caliper, secondly the rim and thirdly the blocks. The rim and the blocks made more difference than the caliper. Yes I know that a dual pivot caliper would have given even more stopping power, but the fact remains that the right rim and block combination gave perfectly acceptable, but not outstanding, braking performance with down market single pivot calipers.
So those who mentioned rims and blocks should bear in mind that they need to be the right rims and blocks.
Oh, and when it comes to calipers avoid anything built to be light, it won't brake as well as something built to be a good brake.
