I also run a small business and put a lot of purchases on credit card.
Nearly all banks have a term in their rewards conditions saying that reward points can only be earned on personal transactions and not on business transactions.
But in reality most banks do not actively enforce this rule.
So you are fairly safe earning points from business transactions. If you are scared, just transfer your points to Qantas points (or other airline) each month, so then Commonwealth Bank can't take all your points if they decide to audit your account.
A little time ago, I sent a complaint regarding my credit card to the Commonwealth bank, and they replied to me disagreeing with my complaint. And then they basically said, by the way, it appears that most of your transactions are business transactions which are not eligible to earn points as per our conditions. If you are not happy with our answer to your complaint, please reply to us and we will review both your complaint again, and we will also look more closely at your transactions to see if they qualify for rewards points.
So basically they threatened me that if I pursued my complaint further, they may take away my points.
I have earned over 5 million points on two cards (Visa and Amex) for business transactions over a couple of years and neither bank has taken away any points. So I believe at the end of the day, they know that if they take away points, you will leave them for another card.
and Jim, the Amex Gold Maximiser Credit Card is one of the Amex cards that gives you 1.5 points per dollar spent. There are other Amex cards providing the same points, thus the Amex Gold Maximiser Credit Card is not the best, but maybe equal best.
Personally I like the National Amex Gold Ant card as it can be linked to a National Business Management account which makes things easier for me.