The other thing that I would note about balance: you will always find something that is under or over powered in a given game. The reason is that since the mix of ships is so random, sometimes a ship is a great counter to everything that the enemy has, and sometimes everything that the enemy has is a counter to it. That's part of the evaluation of your options as you play the game, is choosing what to use for the specific scenario you have. If all choices were always equally viable, then all choices would be pretty meaningless. This is very much a game about Finding The Right Tool For The Current Job.
That said, when something is habitually under or over powered in a variety of scenarios, obviously that's a major problem and we address it as soon as we can. But you can't really compare a period when we're actively adding dozens of new ships per week during a beta of an expansion (or during the 4.0 changeover) to our general beta periods when it's all tweaks and such. It's rather that balance tweaks make things substantially worse than they already were, and they generally make things much better; it's adding new ships that tends to be the unbalances-things-for-a-while activity, because adding one new ship means rebalancing a lot of others to make sure everything makes sense together. Apples and oranges between those kinds of times to now.
In terms of the prerelease, I'm going to get that out the door tomorrow morning. Was going to do it today, but man it's been a long day and I'm just wiped.