I wont bother posting YouTube videos because quite frankly, I cant be bothered.... but, if you have a search and a view of a few Omega vids, you'll be able to see comparisons between Auto and Manual acceleration.
I noticed;
The Speedo rises in a quite fluid manner with an Auto, the Manual equivilent stops accelerating at gear-change (very quick gear changes at that).
The three gear changes required in a manual makes a 0-100MPH dash almost a second slower than the equivilent Auto.
A Manual will accelerate to 60MPH from 0 approximately 0.3seconds quicker (due to 'off-the-line' spurt).
These are all comparisons of like for like 2.5 or 3.0 Omega's respectively.
There are loads of vids. Take a peek, and post your own observations.
NOTE: All the timing I have observed are my quick (or not so quick) finger on the mouse to determine acceleration times.