Why are you going straight to production on a different version, you should be developing / testing against the version you will be using.

I think you are going to have to decide how acceptable the risks are, I would recomend having a test environment that matches the production environment as closely as possible (Some people do have issues that are OS related).

Do you have access to another machine that you could install Solaris on for testing? You can then develop on your Windows machine, perform your testing on a Solaris box before moving to the production server.

On the other hand you may never experience any problems moving between the platforms, as you say it should just be a case of dropping in the jar.