So it sounds like mindscramble has absolutely no idea how rogue dps works (actually he obviously doesnt from his gems), he just simply manages to out play you two. Imitating him when he doesn't even know what he is doing isn't going to help. What you need to do is find out what is wrong with how you are actually playing and not look at your gear set up since it seems pretty clear that mindscramble is out playing the other rogues on the actual encounters by so much that with inferior gear and no idea what stats he should want, he does more dps.
Are you using the right poisons? Are you keeping a near 100% uptime on SnD? Are you using your cd's properly? Are you tricks swapping?
Honestly with the 10% buff, all 3 of you have enough gear to break 10k on saurfang 25.