Hey mate,
I'm a business owner and choose to do a bit of both depending on the financial year and how much tax I will be up for. Meet with your accountant a few months before the EOFY and decide on the best strategy of how much to send to your super fund under the concessional cap and how much to keep in taxed dollars.
Also remember, your FIRE money technically only needs to last until you can access super then you can combine the amounts for your older age retirement, I think there is a good spreadsheet calculator out there to work this all out (search these forums for FIRE Calc Australia).
But being a sole trader the biggest advantage you have is to reduce your taxable income and ( therefore tax you pay) by moving as many expenses as possible through the business, that will give you the greatest return long run.
Just my 5c :)
