Surprised at the Roubaix - would have expected it to be under 10kg, even with the Brooks saddle. Are you weighing it with saddlebag and full bidons attached?
It has a Brooks, those lightweight bendy plastic clip on Crud Roadrace mudguards, two bottle cages, a Ortlieb barbag mount (but not the bag), front and rear lights and a Carradice bagman "Sport" bag support
The SON generator hub is a bit of extra weight also, and it all adds up
I was kind of surprised at the relative weights but the Roubaix isn't a top of the range carbon bike and it is fairly robust so wasn't expecting it to be very light
The Datum I did expect to be heavier than the Roubaix