Short answer, no. As for the 15/mo data plan, you can possibly get away with it because att doesn't have the touch slide as a phone. Don't expect tech support from ATT though.
Your only option is to call Three to see if they can give you an unlock code. I think the only way to do that is via Flash. Meaning you will need to take it in and purchase a service to flash unlock your phone so that the phone will become unlocked. Sorry.
For phoning, the Sony Ericsson is hands down great. The UI is easy to navigate. However you mentioned you text as well, which may hamper you a bit. The keys are a little cramped up depending on how big your fingers are and having a name like Big L, I would assume big fingers? LOL. Well your...
I have been a Sony Ericsson fan since the T28 days when bluetooth was introduced. So I am a bit biased. My wife has had Samsungs in the past and I have to say they are pretty durable phones. As for the SE phones, they are a bit more "delicate" in a sense that they are less bulky, more opportune...