5k rpm isn't enough, downshift twice. No need for a low-geared HD (and they aren't geared that low, they just make their power at lower rpms) to get the jump on a high-revving sport bike (which a 2v duc really isn't)
Actually YES, some of the are.
Yes, they do make power down low (a reading from the book of Duh), but many of them are ALSO geared low, specifically domestic production 883s and XR1200/XR1200X models.
It's not uncommon for them to launch better and stay ahead for about 1/8 of a mile.
But most sportbikes will outrun them by the 1/4.