Haven't used them much. Last few weeks, pretty much every TvZ that gets to broodlord/infestor is either pretty much over or I'm playing against someone who doesn't know what an infestation pit is (MOONGLAAAAAAAAAAAAAAAAAADE!). Generally I have trouble remembering to add the ghosts in as I'm really strapped for cash remembering marines, tanks and upgrades as it is.
In general I just use tanks and eat it. Switching to ghost requires a lot of time and gas. Gas I could spend on tanks! Ghosts with moebius reactor and Cloaking, Cuz without those you'll never get an EMP off on infestors.
Also, infestors are ******* huge. Even when they clump it's tricky to emp enough of them unlike careless Templar. Grrrrrr
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