Pannier rack adaptors for frame with no mounts

Just read through this thread as I'm also looking for a mounting device for my road bike which doesn't have mounts. Do we all agree that these Axiom Streamliner are the way to go?

Having read a few other forums on these, I have a few questions i hope someone can help with:

• Do you ever get your heal striking the panniers?
  
• How sturdy are they when loaded with, say 15KG load? I have read that they tend to move around a lot and in some cases strike the tyre.
  
• Would I be better to get one of these or a Topeak style seatpost mounted job for a week's touring (with minimal clothing/extras)?
  
  

cheers