If your grandfather had taken the test, his results should have been less ambiguous. The state of the art in BGA analysis isn't useful for genealogy yet.
The real value of autosomal DNA testing is matching segments of significant length with other people, which means you share a common ancestor. Many people on 23andMe and FTDNA have discovered previously unknown cousins and broken down brick walls through autosomal testing. Some adoptees are finding their birth families, which would've been impossible any other way--especially considering the draconian laws concerning adoption records in many states.