Yeah, that'll work in a rescue situation but it's a major pain if your second falls and wants to be lowered to that bomber ledge three feet down, but has to wait fifteen minutes until you can rig some stupid shit to get some rope thru the device.
Snoboy: with an ATC you can belay a second, a leader, rappel, lower. With a gigi you can't belay a leader, you can't rappel without scavanging biners from your rack, you can't lower (effectively). You can climb with only an ATC, while if you use a gigi you need another device to belay a leader. So my earlier assessment is correct: an ATC is more versatile than a gigi. I'd buy and use one only for alpine routes, esp. with a three person party. I wouldn't consider it as an all-around device, cause it isn't designed for that.
As for the price, 10 bucks for the gigi, plus 20 for a device to belay a leader, and you're past the price of a reverso or b52 which does it all.