Both hands on flight controls after V1 - tradition, myth or technical fact.

[Capn Bloggs]

Don't worry, Centaurus is from Australia...

I use two hands because I'm a weakling, but mainly because it gives me better pitch-rate control during the rotation.

And if you don't have your hands on the throttles after V1, there is very vey little temptation to re-grab them after a big bang before liftoff, as previously mentioned.