On 64-bit platform there is generally no issue (of larger memory requiement)with using the scalable_malloc.
On 32-bit platform (or 32-bit applications run on 64-bit platform), it may be advisable to NOT overload new/delete, and the selectively use the scalable_malloc/free routines for the few high frequency malloc/free objects. (On Windows, you may also want to enable the Low Fragmentation Heap feature).
There is an additional issue of where an object is scalable allocated from one thread and deallocated by a different thread. This may cause either memory consumption issues or additional latencies. This is not an issue where allocation/deallocations are performed on a call stack (e.g. ctor/dtor of stack frame objects). But it can be a problem when an arbitrary thread can delete an object pointed/referenced by a concurrent queue of object pointers/references.