Good thing with either really... most important is to use as big conduit/tube as you can.
Quote Originally Posted by m_c View Post
Not for something carrying solids/fluids you don't!
You need to keep the air speed up, or it'll drop the solids and clog!
Ok, clearly I was generalising too much as obviously it has to be a balance between the two. This site explains a lot:

http://billpentz.com/woodworking/cyc...fm#DuctingSize