ME Storage Cells make for fantastic overflow buffers. They're also useful as item catchers should a given storage device fill up mid recipe. When your factory borders on several thousand recipes and well over a thousand me cables you never quite know what might happen. I always keep a drive full of unformatted low tier storage cells to act as a compact mod item catch.
If you want to get fancy, you can set up a system that automatically shuffles your item catcher cells into an ME IO should your storage setup change.
Yeah, but having the buffer disks in a drive is just way too hard to keep track of IMO. Therefore I prefer this setup:
I have 3 ME chests with 4k disks at priority 2,3,4 as the lowest buffer for everything random.
All the drives(Priority 10) have formatted disks with either single bulk items(stones, metals etc) or groups of single items(tools, weapons, stone microblocks).
I have a Recycler/trashcan/whatever deletion method used setup(Priority 9) with a storage bus(or several) programmed with everything that has the potential of overflowing its formatted disk or is simple unwanted.
The great strength of this setup IMO is that it is very easy to go look in your buffer disks (or hard to miss the giant colour indication on top of the chests). It is also very cheap as, despite what it looks, since almost all of the disks are 1k disks. When they only store one single type of item the efficiency is much greater.
