Brian: 50% was a random figure. Actually it can be less with a weak pump, and more with a strong pump. With that 20RZ iwaki you don't need to worry about anything, but leaks...
My remark was just a suggestion, and it's about the only thing i have to say about your setup, apart from 'nice'
As for an idea of how your setup will perform, i'm in the process of writing that simulator... In the mean time you'll be ready to fire it up i guess.