The description of the Overhub refers to the old Overbridge version (1.x) and not Overbridge 2.0.
The Overhub is especially targetting the Mark 1 devices (AR MK1, A4 MK1) which uses only USB 1.x. Normally a single USB 1.x device will slow down the complete USB 2.0 hub unless it supports MTT (the Overhub does).
While Overbridge 2.0 doesn’t generally support USB hubs most installations should work flawlessly (when no MK1 device is involved).