The outcome will also depend on if you are riding in a group of DF bikes or solo. I haven't ridden my bent for a few years now, but have been riding a DF Tandem. I think the performance characteristics of the tandem and a fast bent would be comparable. Fast downhill and on the flat but a bit slower uphill.
So in a TT situation it is faster or in a group of DFs on a flat course it is also good.
On a hilly course though I am slower on the tandem (equal ability riders) in a race situation than I am on a solo Df. What happens is that a bunch of DF riders drafting can match the speed of the tandem on the flat and then you get dropped on the hills.