You are right that oral bioavailability is going to suck but it makes no sense to take 1-AD instead of 1-test. 1-AD is going to have the same bioavailability problem as 1-test. Besides, why would you choose to take a prohormone that converts (somewhat inefficiently) to 1-test when you can take the active hormone itself just as easily?
Personally, I would never take any of these things orally. The bioavailability problem makes it pretty much a waste of money and time. I will make an injectable from the powder where bioavailability isn't an issue. Even transdermal preps with DMSO will be more effective than oral dosing.
If you are going to take a 1-test product orally, then 1-AD is the way to go. The 1-test orals just don't seem to work as well. Transdermals are the way to go w/ 1-test.