Well, where to start.
Power Bass is a completely new brand, to me. I don't know If I want to go with a brand I've never even heard of, especially since these will have to last me all year. Take no offense, but I'd need a lot more than the word of one person.
Currently considering Adire Shivas. Basically, it's still down to that and Alpine type Rs. Basically both are the same price. But still, I don't think there's a way of saying R > Shiva or Shive > R. I've basically got a list of every feature I've found about both, listed the side by side, and highlighted which one has the better value. So far, the Shivas are winning.
You're sure they'd work well with 2 cubes apiece, ported? I can also lose the seperating wall, making a shared 4 cube enclosure. If they like box space, that would work well.