Bill,
Here's my 2 cents.
You are beyond where most of us have experience. I applaud you for your efforts!

I think it is a good idea to start where you are at--basically something in the "15-20" size category.
So I would just do it! Somewhere on this board I have a thread about my 1/2 A pusher canard plane. Not sure if I will continue with it or not, but I learned a few things (also they were pointed out to me). Certainly was a bizarre first flight!
I have a similar rc ducted fan-a Fantom ---http://www.hobbypeople.net/gallery/107310.asp
It is a hoot to fly, and when I'm in the mood (which is soon--it looks like above 32F on Monday!) it is a lot of fun. Big open maneuvers and the "swoosh" factor can't be underestimated. It is a single fan of course using a 3s2100mAHr battery for energy.
As a prototype, you might consider changing your plan to a single fan. The only reason is to save a few bucks to see whether there are any show stoppers. A two fan setup requires 2 ESC's (mine has a single 30A ESC). I know that what you show looks cooler, but I am a big believer in "small baby steps" when tip-toeing in the dark! If it looks like it might be a success, then I would go for what you want to do.
Anyway that's my take on it. There are a lot of issues---jets aren't known for their square maneuvers for example. However there is a real "cool" factor here.