I've worn the GMT2c TT (which is about the size of a Sub) and am currently wearing the DSSD. It's a massive beast and it takes some getting used to. Not for everyone, and I feel the GMT/Sub size is more suitable for the regular guy.
However I'm quite big sized, (6ft and 90kg) so it suits me lar and surprisingly comfortable. I would not swap it for the smaller Sub or Gmt since I love the size. Not for everyone though.