HPS (High Performance Street) would seem to be a great product for the hot rod crowd. However, the demands placed on an oil used in a diesel environment is quite different than the demands placed on a gasoline fueled vehicle.
You don't mention which TDI you have other than the displacement so this could be an old rotary pump AHU or ALH engine or a unit injector 'PD' engine. The rotary pump engines seemed to work fine with just about anything that could suspend soot and not boil out of the crankcase. Their issues were with intake clogging at the EGR and puddle accumulation in the intercooler.
Unit Injector engines of course need anti-wear additives and viscosity to keep the exhaust valvetrain actuators from chewing the camshaft to bits. If the PD engine is what you're operating then it would seem to be a good candidate for testing out the HPS claims of reduced wear. I'd use nothing lower than their 10W-40 though based simply on the requirements that VW put on the 505.01 standard. You need seal compatibility, a HT/HS of at least 3.5 cP's, and I would shoot for a minimum operating viscosity of 12.5 cP's average.
TDI's, whether it be the ALH or a BEW engine code benefit from very low soot production due to such low fuel consumption. The engines are heavy on EGR for emissions reasons and therefore can dirty their oil rather quickly. I wouldn't try to do any crazy extended drain intervals with the HPS but I don't see any detrimental outcome from its use either. I would use a 10W-40 viscosity though to get the HT/HS requirement.