OK, I'll make this short and sweet:
As per RAW, missiles generally give their users smaller dice pools, cost allot more and are harder to procure.
The smaller DP makes a homing missile less accurate in a sammy's hands than an unguided rocket.

Thusly, the revised rules for missiles:
1: Attacker makes an unopposed test (agility+heavy weapons) against his target, applying appropriate modifiers to his DP and noting the resulting hits.
2: Defender makes a vehicle dodge success test vs. a threshold of the missile's sensor rating +1, limited by the number of hits in the previous step.
3: If defender fails the test, he takes a direct hit from the missile (assume range zero). If he succeeds, roll 1d6 for scatter and add the net hits from the defense test. Apply nothing else to the scatter roll.

After running the numbers this seems to work much better from the scenarios I've tried. My GM seems to like it too and we will be running some skirmishes and trying it in the next few sessions. Any thoughts? Anything I've overlooked?

correct me if i am wrong, but would this mean that a small vector thrust drone is as easy to hit as a big van?

I was under the impression that thats how it was before. Handling would apply in the defense test and thats the only differentiating factor I'm aware of. If I'm missing something, please enlighten me. In any case, it would be no weirder than a Stormcloud dodging a SAM.

point *g*

I've been trying to figure that out, too. While it might be unbalancing to make it harder to shoot dwarves and easier to shoot trolls, it seems like there should be some rules about shooting at different-sized things. I know there are sized-based rules to get a sensor lock, but are there any rules about actually shooting them?

Yeah. They're on p. 161 in Arsenal.

Not a big differentiation, but enough to make it seem more realistic. I just like the fact that the writers assume at some point we will need to know the DP modifier for shooting a baby.

Chris

Yes, yes we do need the size mod for shooting children. Ive had a character do that in one of my games.