The planet currently named "Home 8" was a real home world which I have already taken with a force of about 60 bc and 560 cruisers. According to the current combat rules disclosed on the forum, and another player's helpful spreadsheet (sorry, I forget the name of the poster), that calculated enough to be able to take a home world with about 50% losses. And on the first test attack, it proved to be correct.
The second test attack (different home world) I had something around 580 cruisers and 120 battlecruisers. That encountered to watch-dog-killing-the-server-in-the-middle-of-battle-bug.
The third test attack (same home world as the second), I had 584 cruisers and 134 battlecruisers. More firepower than the original successful attack and capture of a home world.