Author here.

> I don't know if the authors are here, but if they are - would you comment on fragmentation and the dangers of growing a filesystem past 95-98% full ?

Fragmentation isn't an issue in TFS, at all. Because it is a cluster-based file system. Essentially that means that files aren't stored contagiously, but instead in small chunks. The allocation is done entirely on the basis of unrolled freelists.

This does cause a slight space overhead (only slight, coming from the fact that metadata of the file is stored in the full form), but it completely eliminates any fragmentation.