std::basic_string template specialization - c++

Question

I'm trying to create my own string class using std::basic_string<> with a custom allocator. It's seems to be mostly working thanks in large part to other related topics on stackoverflow. But I really want this to be a drop in replacement of std::string. To that end, it needs to assignable to/from std:string. I tried overloading assignment operators and such but I can't seem to get that working.
The end goal here is to be able to log/track memory allocations for strings in existing code by replacing std::string. If there's a better way of doing that, I'd like to hear it as well.
This is an embedded application so my options with 3rd party tools is limited.
Here's a sample app with the code I have already.
dave
#include <iostream>
using namespace std;
namespace mw_allocator_namespace
{
int mw_allocator_space =0;
template <typename T>
class mw_allocator: public std::allocator<T>
{
public:
typedef size_t size_type;
typedef T* pointer;
typedef const T* const_pointer;
template<typename _Tp1>
struct rebind
{
typedef mw_allocator<_Tp1> other;
};
pointer allocate(size_type n, const void *hint=0)
{
pointer p = std::allocator<T>::allocate(n, hint);
mw_allocator_space += n*sizeof(T);
cout << hex << " Alloc: " << n << " : " << n*sizeof(T) << " (" << reinterpret_cast<unsigned long long>(p) << ")" << endl;
return p;
}
void deallocate(pointer p, size_type n)
{
cout << hex << " Dealloc: " << n << " : " << n*sizeof(T) << " (" << reinterpret_cast<unsigned long long>(p) << ")" << endl;
mw_allocator_space -= n*sizeof(T);
std::allocator<T>::deallocate(p, n);
}
mw_allocator() throw(): std::allocator<T>() { cout << " Hello allocator!" << endl; }
mw_allocator(const mw_allocator &a) throw(): std::allocator<T>(a) { }
template <class U>
mw_allocator(const mw_allocator<U> &a) throw(): std::allocator<T>(a) { }
~mw_allocator() throw() { }
};
}
typedef std::basic_string<char, std::char_traits<char>, mw_allocator_namespace::mw_allocator<char> > my_string;
int main() {
string s1("Hello World1");
my_string ms1;
#if 0
// This doesn't work
ms1 = s1;
#else
// This does...
ms1 = s1.c_str();
#endif
cout << "ms1: " << ms1 << endl;
return 0;
}