If you're already doing log normal modeling of your estimates, and including sick days, social loafing, etc, then you don't need Vistimo Quotes. Just keep doing what you're doing!
This is something I would buy if I had confidence in the simulator.
Why not write a blog or a brief white paper giving some hint of what's going on behind the scenes?
Generally speaking, every bit of energy someone spends being cool (good UI) comes at the expense of energy spent being good. Maybe you've done some serious work on the simulator, but I can't tell from your marketing material.
Why would you assume that? If your model is already pretty much perfect, not much more you can spend your time on than presentation.
I'm not saying you can't make money selling an RNG with a slick UI, you certainly can.