Do you keep an eye on the revs when it hesitates? It'll be easy to spot the revs jumping a bit. If it is the clutch I can recommend the Helix Organic. I fitted one after my stock clutch started slipping (also high load high gears) and it's spot on. Feels like stock apart from a slightly heavier pedal, and apparently good for 400lb/ft. It's handled 350lb/ft for months without issue.
It doesn't sound like typical DV failure symptoms. I'd expect it to lose boost in all gears under load rather than just the higher gears. But it's worth checking anyway. You can get to it through the osf arch liner. VW rev G works well; again mine handles plenty of boost and still feels as responsive as when it was fitted more than a year ago.
It's worth getting it scanned for fault codes; it could be something completely unrelated to the clutch or diverter valve.
