Success in SoCal
I have had similar issues of not connecting to the TMO network when I got my Moto X from Motorola. While under 4.4.0, after playing with some settings I was successful while using the following Settings UNDER Mobilel Network Settings:
Data enable: √ (checked on)
Preferred Network Type: LTE/GSM/UMTS (do not use Global)
Access Point Names (leave it blank) it will be pulled over the air automagically [I will try to enter the APN once I know the LTE APN from TMO]
Network Operators: (selecte it and it will search for the available Networks, use TMO if you are using TMO's sim or ATT if using ATTm sim)
Select Network: UMTS only
Obviously, this applies to a Retail Verizon MotoX that comes automatically unlocked. No need to call the carrier.
One very interesting point, while under KitKat 4.4.0, I was able to reach 4G LTE, it would have the logo on the top right corner. I tested the speed (using speedtest.net) and when near to a cell tower, I would achieve speeds in excess of 25Mb!!!! using TMO's network. On the average around Los Angeles, I was getting 8Mb which is good. HOWEVER, once I upgraded to 4.4.2, I ONLY see the H+ signal and my average speeds have come down to 6Mb. I guess something must have happen with the 4.4.2. upgrade.
The voice and text issues, I did not test, since I use GoogleVoice EXCLUSIVELY for all my calls and since said services uses the internet for all functions of calling and texting, I have not had a problem. So it may help in using Google voice to make calls is necessary.
I hope the this info helps. Ciao.