This isn't correct. When you gate check a bag, you pick it up at the regular luggage carousel. The exception would be if you are flying on a small plane with tiny overheads where everyone must gate check everything except small items.
There are 2 kinds of gate checking. One kind is when someone brings something that ends up being too big or bulky. It is absolutely within their right to charge you the regular baggage fee at this time, but YMMV. At the gate, the airline personnel will tag the offending bag with a proper luggage tag with a preprinted desination and have it loaded with the checked baggage.
The second kind of gate checking (far more common) is when you roll your bag to the plane, and leave it just outside the plane door. The crew will tag it with a bright orange or green temporary tag (not a proper luggage tag with a desintation prepreinted on it) and pack this in the belly of the plane in an area separate from the checked baggage. The crew will unload this at the end of your flight, and you NEED to pick it up just outside the plane door. If you don't pick it up immediately after your flight, it will not arrive to your final destination.
It is certainly possible to use carry-on only for a 5 day trip. When I travel alone, I only do carry-on so I don't have to wait at the luggage carousel, or risk losing my stuff. I also hate to pay the fee.
When travelling with my kids however, I would rather focus on enjoying the journey and be free and flexible. 2 adults and 1 child lugging 6 bags through ATL airport will have a very difficult time relaxing and enjoying. It's like another poster said: You'll have to get it out of your car, into the airport, through the airport, THROUGH SECURITY, to the plane, onto the plane, off the plane, through ATL airport, onto that plane, off of that plane, through MCO.
I put "through security" in capitals because you will need to pull any liquids out of your packed bags and set them aside. They need to be smaller than 3 ounces each, and fit into 1 quart sized ziplock per person. Not per bag, but per person. That, on top of taking your shoes and jackets off. Taking cell phones and coins and keys out of pockets and putting it all into the trays for the scanner. All while trying to keep an eye on one child and 6 bags. Sounds like a nightmare to me.