I use some margin quite regularly for day trades that are closed by end of day, but would I ever use it to load up on a "single gung-ho trade' ?? absolutely not ever.
This is not Las Vegas. The most I would ever risk on a single trade is 4-5%, and even then 99% of trades I risk 2% max. At least in Vegas you can get free drinks while you watch your money go down the shitter.
Why would you ever put yourself in a position where 1 trade could put you out of business? There will always be more opportunities. By never putting more than 2% of capital at risk on a single trade you could sustain a string of say 10 losses in a row and still be in the game.
My Port is up 2.7% today and the overall market was not real strong and I never risked more than 2% on any one trade.
cheers!