The Vorsprung Durch HPVelotechnik will take the short sharp shocks off (potholes, comedy off-roading and so on), but the higher frequency stuff is still down to the tyres. On a Streetmachine style bike, that's more about optimising grip and rolling resistance than avoiding road buzz injury to your hands or feet as you would on a DF or unsuspended recumbent.
FWIW I pump the 40mm Marathons on my Streetmachine to 70-80PSI for fully loaded touring on road, leave it un-topped-up for months on end for unloaded riding (particularly in winter), and deliberately reduce it a bit if I know I'm going to be dealing with proper amounts of rough stuff (which includes Dutch paving). It doesn't seem particularly critical with Marathons, unlike the rear suspension, which has a definite sweet spot for load and conditions.
(I tend to go with the same pressure front and rear, it's not like an upright where the rear carries most of the weight.)
ETA: Possibly useful factoid if you don't have Streetmachine experience: This is the bike where you can have a puncture and simply not notice. On the rear it's almost indistinguishable from a strong headwind, and the front can get surprisingly low before the steering is substantially affected, especially off-road.