How Accurate?

For some time now i have been considering to buy some software; particularly BeerSmith but then i stumbled across this http://hbd.org/cgi-bin/recipator/recipator. I plugged in a brown ale in both softwares, but got a darker SRM and higher IBU on BeerSmith. How accurate do you guys really think the "recipator" is?

There are various formulas for calculating the values we use in brewing. Chances are the packages are using different formulas by default so the calculations won't be the same. They are all approximate values anyway so as long as you stick with the same formulas every time you will get consistent numbers allowing you to compare. Get Beersmith or Promash or BTP and you will be very happy with any of them.