There was some talk on this in the early days, I can’t remember the thread. On paper the MK7 GTD is almost identical to the MK6 GTI in 4th/5th/6th gear acceleration from 40-70mph (slight edge to the GTD, if I remember correctly), but the MK7 GTI is a little better than the GTD in every gear, probably more through the substantial hike in torque than the 10PS it gained over the MK6 GTI.
I'm pretty sure that GTD 4th gear acceleration was comparable to MK7 GTIs 5th gear acceleration, same with GTD 5th vs GTI 6th.