Well Dial Idol has a very strong history. They've predicted a lot of major upsets over the years, so I put a lot of stock into what they say. The only thing is that they don't count text votes... just the call in. Still, they're usually pretty accurate. Typically, they have the person going home near the bottom even if they don't show them as dead last.
It'll be interesting since yesterday there was buzz all over the net about how an idol "staffer" leaked that supposedly the contest was fixed and the final 4 were already chosen (Alexis, Danny, Adam, and Lil). So, if DI *is* right and Alexis goes, the judges will have to be careful about if they want to use their saving power to save her because that will just fuel the rumors even more.