Hey Hannes, I think you're going in the right direction in general. I disagree with you on one principle, though.
On aggro, i'm looking for decent green one drops. i'm not gonna push any other aggro-colors for now, since i don't really feel a need for more than one color, with some splash-support.
I'm gonna stop you right there. At the risk of sounding pushy, I feel it's necessary to emphasize the importance of supporting aggro in most, if not all of your colours across the board. If you've been keeping up with Jason's articles, you'll know that mono-colour aggro doesn't generally result in the best decks. Rather, the most powerful aggro decks are typically two colour, and on rare occasion, three. Supporting aggro in a wide variety of colours allows players to naturally combine them and come up with a nice mix of aggro decks from one draft to the next. But pushing the archetype only in green will mean a couple of things: first, there are only enough cards to allow one player at the table to go into aggro; and second, they'll end up with roughly the same deck each time.
Now, you may be asking: Why is it important so support aggro at all? Couldn't I just excise aggro from the cube altogether, and be done with it? The answer is, yes, you could. I've played cubes with minimal to no aggro support. If that's the feel of the cube you're going for, you could certainly take it in that direction. But I will warn you that the games played won't resemble anything close to your typical constructed or even limited match of Magic. Without the checks and balances that the typical aggro / midrange / control trifecta provide for one another, games boil down to slamming five, six, seven, and eight drops against each other, and seeing who can land the biggest haymaker and be the last man standing. That can be fun for a while, but in the long run, there's not a lot of subtlety if everyone's trying to achieve the same goal of going over the top. The best draft strategy quickly becomes apparent to everyone at the table. Aggro decks provide the important function of policing the slow, durdly decks, keeping them honest and making sure they play a fair game. Without the fast aggro decks, the default strategy is typically going larger than the next guy. Cube environments are more strategic and provide more tension when you can go under the midrange deck, in addition to over.
Now, that's all a bunch of theoretical gobbledygook, but my advice in real terms would be to try and provide support for aggro in most, if not all, of your colours. It's interesting that you choose green to push aggro in, because that tends to be one of the weaker aggro colours, so I might try to make sure that a colour like white, which is traditionally strong in aggro, has the proper support. Then you could pick blue or black, and fill out the aggro quotient there as well.
Taking a step back from the discussion of aggro support for a second, I think that another principle to keep in mind is that as a cube designer, you want to ensure that a wide variety of archetypes are supported. We all have our biases and preferences as players, and we need to be careful not to bake those into the draft formats we design. Even if you're, say, a dedicated control player at heart, it's important to remember that not all of your players will share your playstyle, and that you want to enable them to draft decks that they enjoy. Supporting archetypes at each end of the spectrum goes a long way to crafting a good cube draft experience for your group.
I hope you don't take this post the wrong way, as I like your ideas in general, and a lot of the card selections you're making sound like great experiments. And you may have already thought about all of the topics I've already discussed here. But, just in case you haven't, I thought I might give you a few morsels to chew on.