Shrug, the point of my scoring system was to be that if someone didn't actually get victory(note that is worth a good number of points, could be shifted upward), they didn't really have a great chance of winning. I can see your argument for having the first few be a bit more standard though.
Anyhow, I feel that any secondary measure shouldn't be the point system, especially if we are going to do arbitrary multipliers whenever we feel like it (cough 5x for not doing f&d)--at least until its a bit more balanced. Time to victory seems like an ok secondary measure, but honestly we are going to have to go to more complected schemes eventually if we want to keep it from getting stale.
Honestly I don't agree that the objective should always be to defeat the ai homeworlds. Yes, it should usually be that and it should be hard to win without it, but when we start to limit ourselves like that, it kills the potential for interesting games.
To be honest, playing at diff 7 with no real special rules is a bit boring for me, without something to spice it up I imagine that those of us who are used to playing at a higher diff are going to lose interest rather quickly and if we want to interest new people, we can't really jump the diff up that fast. You see complex scoring systems as detracting from the experience. I see it as a way to have the game interest both new people and vets. Honestly most of the complex scoring systems i can see would involve still killing the ai homeworlds but taking some sort of disadvantage for extra points(thus being able to tweak the difficulty to what becomes challenging to yourself).
Lastly, I'm not sure I'm a huge fan of choosing another somewhat underpowered unit for the GOTM. Sure, if the point is to get x to look at and fix that unit, then go for it, but honestly if I was competing I would skip building that unit like I did the bulletproofs last game. I'd suggest starting new people with a unit that we know is reasonable, say laser gatlings, deflector drones or something like that.