That's an interesting approach. I didn't know Chase had Amazon gift cards.
But one thing to consider, you can order from a site like Adorama or B&H and unless you live in NY or NJ, you don't pay sales tax, which you would at Amazon.
So 8-9% sales tax on $4000 is a nice chunk of money. Are the points worth that much?
Other thing to consider is that if you purchase with gift cards, you may not get the extended warranty or the purchase protection that credit cards offer you.