[Greenbuilding] wall envelope - rainscreen

[John Straube]

Raindrop GreenGuard does help drain, but I dont know if it will resist water well. At least it is not perforated like GreenGauard which DOES let water through. I love their DC14 Drainage board though Dupont DrainWrap is one product which I have tested and we have used on numerous projects very successfully.
The code says 1" for supporting siding, which is actually 1" nominal, which means a dressed 1x3" works.
This 1x3 furring has been used to attach cladding of all types in hundreds of thousands of buildings, so attaching stucco lath or vinyl or fibercement or wood clapboard to 1x3 (nominal) is not even a hint of a problem.
Attaching 1x3 to studs behind foam by using screws at 12" to 16" vertically on center has been done in many thousands of home.  
We, and many others, have built hundreds of homes and now dozens of retrofits (that I know of, many more are likely being done) with 4-12" screws through foam to the studs.
Yet, John you say, "So for 3” of exterior foam you need to fasten 1” battens with a min. 5” fastener thru to the framing – and then secure cladding to that with full 1” depth fasteners. Basically gets unworkable."
This is not unworkable. You either have not tried to do it, or you have done something wrong.
We and others have done this in California, Alaska, Kansas, Massachusetts, Ontario etc etc. Eg all corners or North America.  I have done it personally, and we have had contractors do it given only the most basic of instructions.