Most metro reps are grossly misinformed.
Google "samsung Galaxy S3 metropcs" and you'll find plenty of confirmation for the s3 coming to metro, besides looking around in the metropcs forum on this Site.
You will not get unlimited tether on the $60 plan as it only allows 5GB of 4G data. That's how much data you will be able to use for tethering.
when it comes to choosing the best service one must remember: location location location!!!