By the time you get the GS3 from T-Mo in your hands you will have some real world comparisons to make as I'm pretty sure Missouri City is part of the launch area for LTE from Sprint.
Fortunately you have the 14 days for T-Mobile.
I will truly take a test if LTE is turned on for Sprint within the next 20 days. Im going to think about it overnight and may call Tmobile to cancel my pre-order. Sprint will allow me to get out of my contract by paying them 165 bucks and then I can get the gs3 for 199. I'll just sale the gs2 on CS and make up the difference. However, if I don't see anything deployed from Sprint within this 20 day window i'm gone. Check out the Sprint forums and its littered with complaints about network performance all over the country. Its shameful that they havn't come out and made a public apology or at least offered us loyal customers an additional 50 bucks off the gs3 or at least allow us to upgrade without buying out our current contract. This is a very poor display of customer service. I feel very sorry for those that purchased the iphone 4 because it doesn't even have a lte radio.