Using pointers for sorting is fine as long as you don't care about the order (parent referenced std::set and it's not uncommon to use a set of pointers if you just want to store some objects). Likewise it's fine to use pointers for equality-comparisons as long as the pointer is valid (of course you have to dismiss the pointer when the memory is freed).

I'm pretty sure this memory extension doesn't affect uniqueness of pointers... that would indeed break a lot of software ;-)