I am experiencing this right now. I bought a Note 3 on Swappa in November and a few days ago it was blocked (you can read the full story in my thread). It's a crappy thing to go through. Now i'm scrambling to find a way to not have a useless phone or lose lots of money selling it.
IF you (OP) can, I would say to just save the extra money and get it straight from T-Mobile. If it's a phone you will keep for a couple of years, then the extra $150 or so is worth it for the piece of mind imho.
As for the Note 2 vs Note 3, the Note 3 is faster yes, but it also has a larger 1080p screen (vs 720p on the Note 2). I think the battery life is better as well.
If you don't really need the larger screen on the Note 3, you might want to check out the Nexus 5 as well.
i saw your thread ,i feel bad for what happened with you . thanks for the kind info. BTW did you sell your phone?
and yes ,i dont need a larger screen (as it is slightly bigger and better) i think i would be happy with note 2 screen
anything else can i miss?except the fastness and the screen?