I dont think don bradman would be agressive enough... he only hit one 6 in international cricket. I mean i love and respect the guy and hes great beyond belief.. but there is no real way we know if he would have played hyper type cricket like 20/20 well.
Bradman did not hit sixes (not many anyway) not because he couldn't but because he chose not to. He didn't need to. Not hitting sixes did not stop him from scoring runs at an unbelievable pace. Just to refresh your memory he scored a triple century in a Test in a day going past hundred by lunch, past 200 by tea and crossing the triple before close.
To say that he 'couldn't' hit sixes is bad enough to say he wasn't 'aggressive enough' is ludicrous.
By the way, just as an aside, in 1931 a match was arranged to Test an experimental surface in New South Wales. Bradman was batting for quite sometime and then he walked down to Wendell Bill (his batting partner) and said ‘I think I’ll have a go’.
Over the next three overs his scoring shots were;
1st Over; 66424461 (33)
2nd Over 64466464 (40)
3rd Over 16611446 (27) & 2 to Wendell Bill.
Wendell Bill scored singles on the first & fifth balls of the 3rd Over. At the time 8-ball overs were the convention.
Overall in that innings Bradman hit 14 sixes and 29 boundaries.
Of course, it was a local match and the bowling wasn't world class but just to show that it wasn't that he couldn't hit in the air, he just decided very early that it made no sense to do so when he could score so fast with ground shots.
When young Harvey, on his first Ashes tour to England sent a message to his legendary captain asking for a word of advice, Bradman told the messenger, "tell him if he does not hit the ball in the air he will never be caught and thats the most likely way of getting out" or words to that effect.
Not all of Bradman's Test innings have balls faced attributed to them but most have. These 5743 runs were scored at 58.6 per 100 balls. This despite slowing down considerably in his last series after the war when he was in his 40th year. Before that he easily managed over 60 per 100 balls and remember the only innings for which information is not available are the one's against the South Africans and the West Indians whom he fairly slaughtered.
Compare that with Hayden's 60.11 and you realise that this man was no slouch as far as aggression is concerned.
Besides, he was one of the greatest runners between the wicket the game has seen and of course his skills at placing the balls between smallest of gaps in the field are legendary.
The only thing we can say as far as Bradman is concerned that if he was exposed to this format, he would have been a champion in it as he was at anything he put his mind to.