Efficiency Calculations

I am new to all grain so I was trying to use all the technology I could for help. I was using the following programs:
Brewmate for PC
Sparge Pal for Iphone
Brew Pal for Iphone

Each one told me a different efficiency for my mash. My recipe was a simple wheat that I substituted with chocolate wheat and pilsner. 6/4 ratio. I followed the calculations for Sparge Pal and used 3.1 Gal for 1 hr at 152.5 F. My pre boil gravity was 1.032 and my OG was 1.042. My Brewmate tells me this is right at 70% and my Sparge Pal tells me it’s at 56% efficiency?

After this I am not sure which one to use. I checked my options and both are the same. I like the idea of planning my brews on my laptop and then using my Iphone when the actual brew happens. Any suggestions on software that would work better together? Or any idea why the efficiency was so far off?

Each one probably has a different extraction potential for your grains. Or their calculations are different. Either way, why not just use your laptop while brewing? I use BeerSmith and my netbook comes to the garage with me so I have all my calculators ready. Also, it's easier to post a last-minute question here if you run into an unexpected issue