Well, the answer is both yes and no

Firstly, you say you cannot flash the device so how are you planning to get to rescue mode to be able to copy the filesystems? And if you are using dd you'd need to have the same partition layout in both devices. (and you did not state if the old one is 16G or 64G...)
Hence using tar is better if you want to do the copying.
Note though that bot need to be running exactly the same SW version if you do that, since by copying data from one device to another you can only copy the OS files and not CMT.

I'd rather suggest you flash your device normally and then copy what you need from home partition.
(so what's the problem with flashing anyway, you did not tell what goes wrong with it?)