I like most of the suggestions I am reading. Personally, I might consider a few changes.
The razorbacks are pretty nice and shooty, but I'd drop them (they are still rhinos at this point). You will need your tactical marines in the fight, which they can't do inside vehicles and they can no longer hold or even contest an object while in a vehicle. Also I think AV 11 vehicles give your opponent First Blood to easily. That will free up points.
I would give your sergeants melta-bombs. I'm not sure power weapons are a good choice either due to challenges, but I would keep them for now and play-test them. In 4th and 5th Ed I gave every Sgt a Power fist, but those days are gone. :-(
I would consider dropping the landspeeders. They pop much easier now (I can't make a 5+ save!). I would get a Storm Talon for anti-air capability. Don't rely too much on your Aegis Def. Line Quad gun.
Keep the 10 terminators and if you struggle with this list, practice, practice, practice before you re-vamp it...