You only score with your tanks in the enemy deployment zone. Have you looked at the size of the deployment zones in 30K? They are SMALL except for one of the deployments- Hammer and Anvil. I've actually had to place stuff in reserve because I couldn't physically place the models in my deployment zone. With that being said, only three of the six missions out of the book use objectives. Onslaught places one objective marker in each deployment zone- and you only score points if you control the enemies objective marker in their deployment zone at the end of the game. Dominion uses five objective markers that have to be placed OUTSIDE the deployment zones (I.e.; in No Mans Land). War of Lies uses one objective marker placed in the middle of the table- you could get lucky and roll Ambush for the deployment and your opponent is the Ambushee, but I wouldn't count on it.
Basically, your "scoring tanks" would only matter in one mission, maybe two. Scoring units, however, matter in all six missions. I wouldn't count that as a large "plus" for your army, more like a "Oh yeah! I get a bonus in this one mission!".
I might argue about transports scoring, as the book specifically says transports can't score, but I understand they have the tank descriptor for your RoW that makes them scoring. I'd insist on a dice off for that rule, unless/until Forge World says otherwise.
It's still a great list, and would be a lot of fun to play/play against. I'm very impressed that you actually have a Ordinatus Sagittar! At 700 points, it's also a very big target. Funny enough, the shield on it only works for D weapons and doesn't affect the Vehicle Damage chart at all. You basically have an
AV 14 tank with a 6++ and 14 hull points. It's the ultimate definition of a Glass Cannon. Still, it's an awesome model, and if I owned one, Rule of Cool would say I HAVE to play it.