Yes, in file systems with lots of small files and high churn, this can result in very large replays because an entire 2 MB block will be captured in a replay when only a small amount of data has changed. For example, corporate file servers and email servers. This is one of the best practices for Exchange systems and can significantly reduce replay size.
I'm new to the storage admin world, so please forgive me if this is considered beginnner knowledge.  I just want to be sure I understand things correctly.  The data page size in our Compellent environment is the default 2MB.  If we have a WIndows enironments where the average file size is 12KB and we set the default allocation size for the Windows volume to 16KB, how is the data written to our Compellent?  Will a 128 16KB blocks be writeen to each 2MB page?  If so, when data progression occurs, the entire 2MB data page on will migrate between the tiers, not just the 16KB blocks, correct? Thanks
Compellent Page Size and Windows Default Allocation Unit Size