I have been running with a CRD3+ since late feb 2016 and done ~16.000km (mainly on 2+2) in my DSG 150tdi, and I have found nothing but joy using the DTUK box. Unfortunately, I haven't had the opportunity to put it on a dyno, but I can tell you, that I would never drive without the box mounted, the difference between stock and this is quite huge. So far it has worked flawlessly in all regards, much smoother ride than standard, excellent pulling, no juddering, no soot, same mpg as standard - so a lot of enjoyment and smiles on my face.
The other week I had a chance to try a stock Leon 184tdi DSG - I wouldn't say it was dull, but it just didn't feel as alive when pulling away compared to my own car, so there's definitely a difference you easily get used to. In this case when comparing my 150tdi with stock 184tdi - I think it comes down to a matter of difference in torque and when it kicks in.
I am, as stated, now driving a DSG, previous I was driving a manual leon 150tdi with the former dtuk CRDT 2 channel box - and there I had some issues with judder from low rew in some situations, but as stated above, this has never happened in my current setup.