Wait. Didn't I... Wasn't he?... ... Nevermind.
Whelp I have to say that I just don't like venerable dreads anymore. Normally I just give advice, but here I would strongly recommend you take out the venerable. For their points cost they're O.K. in 6th, but most weapons that will penetrate you (such as meltaguns), so that you can use the venerable rule, are AP1 or 2, meaning that they're already going to make your vehicle explode half the time anyways; and if they don't then you're still going to be immobilized or have a weapon gone. The extra BS is okay, but with a plasma cannon the extra inch just isn't cutting it for that huge of a points sink. A regular dread will do just fine. Frees up a bunch of points for other stuff.
As for the command squad. Weh. In a 1500 points match, that command squad will be smashed aside like the fist of an angry god, especially after it drops from its pod. I have one with my captain in my 1k points list where, with his thunder hammer, he's great at challenging and such, but at 1.5k he and his squad will die quickly. Space Marines unfortunately are just terrible at close combat unless you're Blood Angels, Black Templar (arguably), or Terminators. Even then they're iffy. For that 220 points you can get Assault Terminators, as cliche and overused in lists as they are, and have points left over.
Other than that the list looks pretty good like the last one. Hope this helped.