Wouldn't you want a developer's phone for this? One of the Nexus line for instance? Lots cheaper.
Texting is hardly cutting edge stuff, unlike a first person shooter games.
Oh, wait... A tax write off, or sneaking it past the holder of the purse strings...
AHEM, (cough), Well clearly the choice comes down to the One X or the SG3, and you would want to appeal to both of those markets, but the ONE is on the street today, but the SG3 may have a bigger market segment. On the other hand they are similar enough, that you could go with the One today and have your app ready when the Sammy hits the street.