It really depends on the rifles in question. The bullpup aspect itself does not mechanically change the accuracy potential.
My experience with "good" bullpup LR rifles is limited to a couple dozen rounds through a DTA SRS.
Bullpup rifles tend to be more rear heavy which can make them balance differently off a bipod. FWIW, the "top 308" shooter at the 2010 Steel Safari shot a 20" .308 DTA SRS (but it did have a big .338 suppressor on the end).