Commodity futures demos are very limited. However, there is an demo or used to be for J-Trader. However, I never used it so I can say how good/bad it is. Just something you may want to check into.
I don't trade the news more of a position trend trader. So I have to ask whay do you mean by "straddle" technique. I familar with option straddles so I would imagine this is something in the same area. Thanks for your input.