I was almost sure I was going to use a shiva due to wanting a small footprint but now I'm hearing things about the tempest just killing anything else in it's way that has a 12" diameter. Can anyone help me decide? What would be the differences between the shiva and tempest sonotube as far as performance is concerned? Figure tuning to be around 16-18Hz. Height is not an issue but footprint is kind of important. What are the options? Thanks!