I have a set of the 5-pivot Deltas on a bike I don't ride often, but have ridden enough to have opinions about the brakes!
For me they work as well as a reasonable set of single-pivots, I don't notice any real difference in braking between them and the Superbe Pro I have on another bike. The thing I don't like about them is how close they are to the tyre. A small amount of dirt on the tyre and there's all kinds of rubbing and scraping noises.
I haven't taken the bike down any big fast downhills but given how they work on my normal rides I can't imagine they'd be any worse than anything else. I don't know what levers they are being used with, I don't know how much difference it would make as long as they are some type of Campagnolo Record.
