Signed up for AC just to post here.
I got the first (second!) Moto X from my local Sprint store on September 12th. The first unit they activated bricked in my hand after 3 swipes. That made me nervous but I was tired of my Evo Shift and this was the first phone in a while that I was actually interested in.
I've LOVED my Moto X! Until the past week or two. My voice began cutting out, just a little at first and I figured it was nothing. Fast forward to the last three days and it's nearly impossible to have a conversation. I downloaded the OTA update just a bit ago, my guess is that the OTA caused the problem with my unit. I've been to two Sprint stores and they were both clueless as to this problem.
So to answer the question of the Sprint update; no, it has not solved this problem.
Also, while I keep hearing how Motorola makes the best antennas available in a smart phone my Moto X always has a weak signal compared to my wife's iPhone and my old Evo Shift. The weak signal indicated hasn't translated into any problems but it is a curiosity.
I'm super bummed out and rather pissed at Sprint for not knowing anything about this / seeming to not give a crap about my issue.