Not really, no. I'm more inclined to think that DT ammo will usually come reasonably close to advertised velocities when shot from guns with similar barrels and that reported discrepancies are most likely due to variations in altitude, atmospheric conditions, or just certain lots of ammo. That's my hunch, but with the limited information that's available, I can't really make a very educated assumption.
Good to know. My own stash of DT ammo is also dwindling (I'm down to just 19 rounds of their 180grn XTP loads) and I'm trying to decide if I should order more. I've always preferred Double Tap over Buffalo Bore for 10mm ammo both because it is less expensive and because DT offers a much better selection of bullets in that particular caliber.