Well, I looked up a little about it and its solarbord.

I think the link below is what you're asking about. I'd like to hear what forum has to say also.

Here is a link that might be useful: solarboard

I, and the original poster, would like to hear some opinions on this product. Thank you.

Yes, I would!! lol

I have a radiant barrier. It wasn't very expensive and often worth it (and often not).

Radiant barriers are helpful with an unvented attic and ductwork in the attic. The problem is that this situation is not ideal. But it is common so a radiant barrier should be used if this is your situation.

But - a better way to build would be to put the ductwork in conditioned space. Or seal the attic...

A radiant barrier does help even if ducts are in conditioned space, but it stops becoming cost effective. Much more effective to put the $600 into increasing the attic insulation. Even with the ducts in the attic, you are probably in the 10 year payback range in much of the Southern US.

There is a good study at NREL that can be found - it has the benefits in different climates based on ducts in the attic or not.

"Unvented attic" should read "vented attic". This is the most common type in new construction in the south. Unvented is the same as sealed and usually involves spray foam which is obviously expensive.