My 2007 Exige did have some pretty thick black foam insulation around the hose that does not appear in the pictures. In the pictures you can see the bare corrugated plastic tube, but on my car it is covered in black foam. Does your 2006 have that? I would still wrap it with Frost King if I had sufficient access.
I think I understand what you mean about the one-piece radiator blocking piece, so does that mean that it is unnecessary to plug and insulate the center section, or would it still be beneficial. I didn't seem to have sufficient access to that either, I really couldn't cram my hands in there. Perhaps someone with the clam off of an Exige could offer an informed perspective or better yet some pictures?
My AC performance has actually been very good. I do not have experience with any other Elises or Exiges, but mine was able to keep up in high 80 degree F weather so far, but I live in south Florida so I might as well squeeze every bit of performance out of the system. I will not be taking the clam off to do so though.
I did drill out the driver's side footwell panel. I left the passenger side because it is only partially blocked so I want to see the difference with removing the completely blocked driver's side panel first.
My Exige has the driving lights in the lowermost center grill and right next to the lights there is enough room to slip an arm in so I can actually block the front vents without removing anything. Unfortunately Home Depot did not have black duct tape, so that will have to wait for another day.
Acumen, I have an '06 Exige and made an effort to wrap the A/C hose ...