I would have said the exact same thing before purchasing a high accuracy lab balance for measuring hops. It's truly amazing the wide range of electronic balances available these days.I bought an high precision balance too for "testing" hops and spices (I make hop/spice's tea to test them). It has precision of 0.01g and measures from 0.05g to 200g that means still 5 significant digits...
Which platform/language are you using to save the XML document?Actually I worked on the mobile version of a popular open-source italian program. I used .NET 3.5. This doesn't support BeerXML. Soon I'm planning to make a my own brewing software for windows (.NET) and android (java).