Josh, here is my .02 worth. I realize that the HDL20a is easy to cross rent in your area, as it is in most. If it were me, I would start purchasing the HDL30a since it is a significant upgrade to the HDL20a. I would get enough of the HDL30a for the delay towers and then rent enough HDL20a for my main tower. You can then spread your purchase over two years or more instead of doing everything in one year. Cash flow. It also gets you started down a path where you can get a better sounding box than the HDL20a with more features and still do the shows you are moving into.
Just a thought.
Bill