Does ReOrg understand PFS-2 ?

No.

A disk optimiser is under development. It will consist of 2 programs.

The first, Quick DeFrag (QDF), will move files around to remove fragmentation. You must have large amounts of contiguous free space for this to work. It works by copying any fragmented file from one place to another.  This may be released free as a demo.

The second, Full DeFrag (FDF), will perform a full optimisation pass. Files AND free space will be optimised. This will be a longer process but will not need to be done that often.

There are some ways to minimise fragmentation.