Isis tells me I don't have an enhanced SIM, even though I was running it fine on 4.3 and I do. I think it's just not compatible yet and they are really slow. I emailed their support a few days ago asking when they would be compatible with KK and got no response whatsoever yet.
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To the best of my limited knowledge, the enhanced SIM is really just the SIM that comes with the new phones. I had an old SIM that I transferred to my N3 and it didn't have the secure element that is required to run Isis. It's interesting that it works on 4.3 but not 4.4 after my discussion with the Verizon rep the other day (when he almost busted me for being rooted). He asked me what version I was on and I told him 4.4.2 and he seemed to think it should work.