Really. Piecestore had no periodic dip in disk (and node) performance. It just was almost constant 
(How do you solve slow file deletion on ext4?). Even if we donāt mention file deleting - have you forgot filewalker? It tooks hours, sometimes even days of intensive disk reading on typical filesystems just to calculate occupied space and trash correctly.
Iām happy I moved all my nodes to hashstore. Now I can use disks with āstandardā filesystems ext4 or xfs without dealing zfs and vdev wearing out SSDs. I even can migrate node from one HDD to another and it takes hours, not weeks as it was with piecestore. Servers with nodes now has less RAM usage and much less LA.
The only reason to not move from piece store is dying disk. When your could lose only few pieces with piecestore you can lose big log file or even whole hashtable due to bad blocks.