Moving from unlocked iPhone 3G to TMobile Optimus T - questions

Hey there! I have had T-Mobile service for years, and moved from a Blackberry to an unlocked iPhone 3G, which I currently have. I like the iPhone, but can't take advantage of a lot of things, and not sure if I want to wait on the iPhone 5 coming to T-Mobile or not.

I can get a LG Optimus T on Craigslist for about $75, and sell my iPhone 3G for $150 or so, make a profit, and move to the better Android system.

I played with the Optimus in a TMobile store, and liked it ok, it seemed a little smaller than the iPhone 3G, but has more features and is newer. I think the iPhone 3G is like 2007/2008 technology, and the Optimus T is newer.

From what I understand, I would get true multitasking, Android OS, FM radio, great apps, and some good features.

The things i may not like are the smaller size, and just the unknown factors right now. I also have a Mophie Juice Pack to give a LOT more battery life for the iPhone - is there something similar I can get for the Optimus?

I tested the G2X and liked it a lot, but not sure if it would be the right phone or not.

Has anyone else gone from an iPhone 3G to this Optimus T? What are your thoughts? Also, some of the listings on Craigslist are for a Metro PCS. I cannot use this with T-Mobile, as I understand it, right?