Java and Go are pretty similar at the language level, and you're right that the advantages of both are more applicable in large systems. For a small business situation something like Ruby may well be a better choice.

Java has a more powerful type system (though still poor by modern standards). Both have weaknesses regarding error handling - Go encourages you to err on the side of repetitive code, Java encourages you to err on the side of handling errors only at very high level, I'm not sure which is worse. Java has a much bigger ecosystem and better tool support, though a lot of it is written for pre-C10K days and assumes a "1 thread per connection/request" model - but frankly for a small business type situation that's fine. The go concurrency model is overkill at the low end and not flexible enough at the high end, but if you're in the sweet spot then you can write code more efficiently there than in Java.