It is as bad. I have full ilv710 gear with 725 weapons on DH. At best you'll push 70-80k during burst. My shaman with ring is pushing out 100-120k in comparable gear. My 730 monk with 795 ring is easily doing 160-180k DPS.
Don't even try to say that things are comparable when a class is missing a broken OP legendary ring that essentially gives you a huge damage cooldown.
Now, does that mean that people should turn you down for mythic dungeons? No, that's retarded, mythic dungeons were made for 685 ilv gear.
But in heroic/mythic raids it does matter how much you contribute.