Late to the game (at least I made it back!) but here goes.
The Request Dealloca... will only work when the VI holding it and its hierachy goes idle.
Go with Mark's sugestion about reading in chunks and writting out chunks. even if you get it working for the files size of today, tomorrow the customer will want 10X as large. Doing it in chunks is in actuality as close to minimizing memory as you can get.
