My 2.0 JTDm has had the same characteristics since I recently purchased it (21 months old when purchased). The contrast between this and my 156 JTDm (150bhp) is very noticeable, the 156 would pull like a train,especially when taking off in 2nd gear but in hindsight I did keep the revs up and slip the clutch to achieve this. I'm now coming to the conclusion that it's just a characteristic of the 2.0 JTDm. I've recently been watching the turbo boost gauge when taking off from standstill and find that if the boost is at 0.8+ bar when lifting the clutch and keeping it above this using more gas, quick off the line starts are possible. The only drawback is that if you've just come to a standstill it takes a second or two to spool up the turbo. Next trial is 2nd gear take off using the same criteria, thus avoiding the need for a quick gear change to achieve a resonable mph.
The function of man is to live, not to exist. I shall not waste my days trying to prolong them. I shall use my time.