When trading with CFD's, you are only charged interest if
- you hold the shares "overnight", and
- you are trading "long".
If you are trading on the short side, then you earn interest if you hold the position overnight.
If you buy and sell within the same day, no interest is charged or credited on the trade.
If you are trading stocks in the ASX20, for example, you are only required to put up 4 to 5 percent of your own money. So, if you are paying interest on the whole position, then you should be focusing on trading stocks that require the least cash from you.
The margin requirements for stocks can increase markedly for those with smaller market caps. I focus almost solely on the ASX20 and ASX50 stocks that have high liquidity and lower margin requirements.
Brokerage is cheaper with CFD's. You will be paying around .08% and/or a minimum of $8 per trade, depending on who your broker is and your monthly turnover. Also, those who trade frequently will have their monthly fees rebated.
For the experienced day-trader, wanting to make the most of his capital, CFD's are a great product. They are not without risk, however, so you need to choose stocks wisely, follow strict risk management principles etc.
cheers