I have actually heard good things about the Hobbyking covering. There is another source for a similar covering that I ran across a week or two ago. Appears to be essential if not the same stuff for about the price. I will have to hunt it up later.A guy built a 200% Kadet Senior and covered with it.
I have a control line Bi Plane I started a number of years ago then moved during the build and never got back to it. I suspect on the 10 acres in Missouri I will find a spot to fly it on. Or a bit of chain saw work can make a place. Will need the fire wood any way. I will cover the bipe with Hobbyking covering.
I have used the iron fabric once. There was nothing wrong with it. Just a bit heavier than non iron on. But I found I simply preferred to dope my fabric down old school. There is also SIG STIX-IT Heat-Activated Covering Adhesive. Smells as bad as dopeing and will fry just as many brain cells with out proper ventilation. I will likely just stay with dope adhering my fabric. Familiar process and no added expense.
You don't have to wait to do a big and amazing plane for fabric. I have used silk on as small as a .20 sized plane. The same size as you are building. Just can't get carried away with trying to achieve an out of this world finish. The weight gain can get there in a hurry. And before I used silk I used tissue or maybe more correctly silk span (?) and dope.
Ken