Actually, the ATK is for any i.MX SoC that Freescale has produced.
The limits are that we have not developed directions here for using it with other than the K3.
No real reason to, the other established procedures here work just fine for the other machines.
Now K3Flasher - that is limited to the K3 because it only has support for the K3 SoC hard coded. It does not contain the details required to setup the other i.MX SoCs.