Quote from KS96:
IB may indeed offer tight spreads, but if you are trading small, commissions + interest charges (if you keep overnight)
are expensive! (own experience)
Calculate the costs of your trading style/size before commiting to IB.
You may be much better off with Oanda.
If you are not skalping but holding for a few hours to
a few days, the advandages of ECN dissappear.
Your stops will be further away than the shortterm
price action on entry. I don't think any broker affords to
intentionally move the price against you tens of
pips (due to the huge arbitrage opportunity that this
would create) just to take you out.
Furthermore, the longer you hold, the smaller you will trade
(unless you don't understand risk). So, commissions &
especially interest charges will matter.