I think the delay you are experiencing on power delivery is just normal Turbo lag. The 3.0D generates plenty tourque, but it takes a little while to arrive. I sometimes get caught out with mine when I floor it from standstill to pull out into traffic and sometimes it feels like the engine has fallen asleep for a moment... then bang, the turbo gets up to speed and the massive tourque arrives and off you go.

The transmission slam that is talked about on the forum is mostly the thump you can get when the tranny shifts into first gear too agressively when you come to a slow stop. This can be improvd by resetting the adaption (as has been mentioned) but If you do not change your driving style it will likely re-learn the same habit. I found that re-setting my adaption and then driving very gently for a while keeps it at bay.