uniqueIdentifier was added in 2.4.x to address the need to ID a device, but you won't see it back ported to CIQ1 devices. When the 1.x/2.x spit occured, they put all the 2.x functionality that would fit in the 1.x VM, and there's simply no space to add more to 1.x.
We'll be something similar with CIQ3, where not all CIQ2 devices will move to CIQ3 (the vahr and 735 for watches) and new things like Menu2 likely won't be available on CIQ2 devices. Looks like there will be more memory for things with CIQ3 too - a 645m with CIQ2 has a max app-watch app of 128k, while on CIQ3, it's a meg.
