I've played a lot on 4.xx (latest release) and this game is truely awesome. It is the best Star Trek game available and provides a very unique experience.
My only complaint is that with the Borg there really is no way to currently have a 'balanced' game. In my opinion if they could be only slightly powerful until Light IV or even V is developed. To prevent them from getting beat down early on they could have ships that are very powerful on defense but more moderate on offense, and then when they get there Light IV or V then really crank up the power.
Another option would be a Borg type scenario where you can develop without their presence and then when the final Civ develops saucer seperation they spawn as a new Civ with a small fleet and they grow from there, or a scenario using the galaxy map with random events that could act as the Borg infiltrating deep into random areas of the map, and they could also have victory locations within the other Civ's territory.
Just musings really, I'll play with them turned off for a more balanced approach and then turn them on for a more risky game.