The CyanogenMod nightlies can be somewhat unstable at times however one of the things that I use all the time is the headsets with the mic built into it. Unfortunately in CM10 nightlies this is broken (bug report here). If you haven't been following, a leaked unlocked bootloader was found and can be successfully ported into the Verizon Galaxy S3 to give you a full unlocked bootloader of the device. Which means, we now have a full fledged working ROM. We kind of did with kexec but not 100% and after a number of reboots. If you haven't unlocked your device, first you have to root the phone without the use of odin for Windows, OSX, and Linux - instructions here. Then just download the "EZ-Unlock" from the Google Play store and click unlock to unlock the bootloader. Then from there, load clockwork recovery and flash the latest nightlies from CyanogenMod 10. If you want to fix your headset, download Audio Routing in the Google Play store and when inside the app, buy the $2.99 version to allow call adjustments during an actual phone call. Where it says Headset Plug Signal, select ALLOWING headset plug. This will allow the headset to work while making calls.