If you want to trade as safe as possible you should only trade 1 contract. Trading zero contracts is safer but then you don't trade. Because you cannot trade less, trade 1 contract against your whole fortune is the lowest risk you can take. You see, it is possible to answer the question correctly.
That's too low by an order of magnitude -- http://bit.ly/1GG6zLf -- and, no, it never "used to be" $500.
What if I have an undisclosed edge and execution method on par with forum legends...could I succeed (with size from 20-100 contracts) daytrading with AMP's 300 USD leverage on the ES?
From what you posted till now I assume that you will never reach what the legends of ET reach. You should follow Marketsurfer. He knows how to make "a killing" in the markets. Although he never did it himself. There is only proof that he only killed clients portofolios thru a fund. It was more "getting killed by the market".
Put your (small amount of) money where your keys and mouse are and pass a TopStepTrader combine and share the results.
I'll give you the benefit of the doubt and assume you're bright enough not to trade as the weakest hand, without even enough margin to hold overnight...
I suppose it is adressed at me. I past that stage already years ago, but skipped it . I don't feel the need to show any results of trading as I trade only my own money.
He never said he would be holding overnight and he has a crystal ball apparently, so $400 will do him just fine to daytrade ES.