Is this the speed reported on the pool site after several hours of mining?  (1) Don't trust the numbers the TM-IV is giving you on its status page. (2) It takes several hours for the hash rate on any given pool to stabilize.  I've noticed the rate typically climbs slowly for several hours.  (3) Make sure you have the latest firmware update.  I've got 5 TM-IV units, and each of them run (with slight variation) at about 1.605 TH/s on Slush's pool after latest firmware update.

I received my "January batch" miners in late February, and have been mining steady for about 40 days.  I've already solved 3 blocks.  You should do proportionally as well.  I can't speak too badly about Cointerra.  It wasn't 2.0 TH/s as advertised, but they are performing much better than the KNC Neptunes at this point.  So we take what we can get.