Recompiled Guardian Module is vendor trash, Shifting Cosmic Sliver is only useful if you really need the fort brew cd a little faster, dunno when that would be the case. Feverish Carapace is ok defensively, but I would say worse than a stat stick in general. You can probably stick with what you are using right now, unless you have a really high ilvl carapace, then you can use that.
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But it is my class fantasy to never be hit by a boss....