Law of unintended consequences
So to thinly provision your space costs an extra $695 per server - why not be a bit helpful and indicate how much 3-Par storage $695 would buy.
There are vendors out there who include this capability within their own suite of software, for lesser charges, by understanding the windows NTFS file system and allocated blocks.
Simple dependance on zero filled blocks is 3-Pars limitation here.
In the end it would be helpfull if Microsoft fixed this with a simple delayed process to zero fill blocks which have been released by deletion.