You're lighting never ceases to amaze me! Every time I see your photos I start thinking I should just stick to HSS capable speedlites and abandon the thought of aquiring some Alien Bees.
A lot depends on when/where you want to shoot. If just want to do light fill in good ambient the speedlites are a great tool. But if you want to use the lights as a primary source then there big benefits to the alien bees.