There is an issue with XA2 TA partition backup, there is no known way to do it. This means that XA2 phones cannot be restored to their original state, or claim guaranty.

In terms of specs XA2 is marginally better that X, but I think the overall UX will be much better, at least for the android environment. How much of that will be supported from SFOS X is not known yet.

Also XA2 has more variants from X and it seems SFOS X will be supporting some of these variants from the beginning.