The SoA transformation makes sense to me and is quite general. The EoA transformation on the other hand feels like a rare special case though it seems perhaps less rare for the OP.

Either way, these types of optimizations are typically marginal in the context of end to end performance of most programs. It's good to have some knowledge of these kinds of techniques, but most of the time it makes sense to do the thing that is most straightforward to implement and optimize later once the program is already working. Of course if the problem maps neatly onto EoA then that should be preferred in the initial implementation. I though in my 30+ years of programming cannot think of a particular problem that I have solved that would have been enhanced by this.