I've been looking at this scope as well. Lots of positive reviews on the vortex.com website. From my understanding they are more or less the same as the HSLR sfp scopes (also have lots of good reviews) with a different (likely better in my opinion) reticule and an exposed windage turret. I have a standard viper 6-20x44 and although I'm still a newbie it seems like a really nice scope for the money; clear glass throughout the range, built to last and the turret clicks seem crisp and repeatable. If the HS-T can improve on the standard viper I would be more than willing to throw down my $650.
Would like to hear others opinions as well.