but some of the enemies weren't used very effectively. The seeker drone was pretty much useless throughout the entire DDA. Never mind about that - I see that you meant it to be that way, but you should get closer to it anyway.
Also, try not to let the lasers fire all at the same time, since when they do that, there is a moment when there isn't a single one firing, and there are moments when they're all firing, and there's no choice but to run away from them. Spread out the laser drones on all sides, and don't place them all at once (place one laser drone, then some enemies, then another laser drone), because that causes the enemy lag-time to stagger the firing of the lasers.
With the rockets, you sometimes ran away from them. None of your propulsion should ever carry you away from the action - you should always keep an eye out for possible close calls, such as going between two rockets, and work to get those close calls. One-ways are very useful for this, since you can z-snap them to the exact pixel you need to get the closest possible close call. For example, instead of the left-downwards facing launchpad next to your starting location, you could do something like this [pastebin.ca]. (Whoa, paste #1233333)
Besides that, I don't have much else to say, other than to keep experimenting with different propulsion methods. You may also want to clean up the leftover gold that isn't collected by the DDA.