Paul
Providing the finance products are separate products and not "under the one umbrella" as one facility, I don't see a problem – from a Tax Office perspective. If they are one facility, the Tax Office would apply Part IVA of the Tax Act which basically says that what you have set up is a sham and they remove the tax benefit and charge interest and penalties.
Obviously any strategy that reduces your non-deductible debt quicker than deductible debt will have some after tax cash flow benefits.