They sound virtually equal then... Other than changeable case sizes...
The only thing that would get me to buy a new GBA flash cart though is extra features like maybe rumble pack support, solar support, and motion control, compatiblity for GBA/DS game links (all types of linking between GBA and DS carts used over the course of DS release history). Also I want save states.
However, I own all the weird GBA carts that have motion, solar, or rumble already.
I'd be especially happy if the rumble worked with DS Rumble compatible games.