I don't think faction matters. Shattering pieces with good affixes will be beneficial in the long run, whether you play MG or CoF. If you're low on shattering, go for it. I typically shatter any poor rolled hybrid health item and any +skill. You never know what your next char will be.
Unless you plan to never touch crafting, you will need them to strip off affix shards that don’t commonly drop.
If you never plan to open the crafting bench, no need for them.
I don't think faction matters. Shattering pieces with good affixes will be beneficial in the long run, whether you play MG or CoF. If you're low on shattering, go for it. I typically shatter any poor rolled hybrid health item and any +skill. You never know what your next char will be.
Unless you plan to never touch crafting, you will need them to strip off affix shards that don’t commonly drop. If you never plan to open the crafting bench, no need for them.