They would have the same CDMA bands but different LTE bands. In principle the ROMs *should* be compatible because LTE is the same technology on either band, all other things being equal (and they never are). And judging by the posts on the topic, they aren't.
It could be that there is a different antenna design as the LTE frequencies are quite unlike each other.
I wonder if a Verizon LTE SIM in a Sprint GNex or vice-versa would still be able to access the respective CDMA networks, assuming the slot is unlocked/unlockable? I know the CDMA subscriber identity is stored on the SIM for LTE devices, but again the software could be designed to avert that.
It could be that there is a different antenna design as the LTE frequencies are quite unlike each other.
I wonder if a Verizon LTE SIM in a Sprint GNex or vice-versa would still be able to access the respective CDMA networks, assuming the slot is unlocked/unlockable? I know the CDMA subscriber identity is stored on the SIM for LTE devices, but again the software could be designed to avert that.