I'd only attempt it if you're sure you can either protect the starbase or sneak it in. I good idea to help pull it off is to attack an enemy territory while sneaking in a migrator. Pulling your opponents attention away from his hw is a good way to get a starbase constructed before your he can destroy it. If your opponent spots it before its complete you may need to run in and protect it. Failing this rush can make this pretty hazardous for you so be careful.
