Thanks for listing them! See my comments below. > Nullability What do you think of boost::optional? > Polymorphism unique_ptr is probably the wrong choice h

Thanks for listing them! See my comments below. > Nullability What do you think of boost::optional? > Polymorphism unique_ptr is probably the wrong choice here. You should be using ptr_vector: http://stackoverflow.com/questions/9469968 http://stackoverflow.com/questions/9469968 > Reassignment/swap The indirection and heap (de)allocation also imposes a slowdown, though. Have you actually experienced this to be worth it in some cases, or is this just a guess? > Release I don't think this is a valid reason...? This is a pretty common idiom for releasing value types: Type().swap(existing); // release 'existing'