Reversing lenses: Using 2 lenses OR direct to camera

[sid]

I have been reading a lot about macro and reversing lenses on this forum. I have also tried using a macro coupler to reverse the 50mm to the 70-200mm. I've also read posts talking about reversing a lens directly to the camera body and seen some great macros taken by Tom Hicks over on the FM forum using this technique.
So, my question is, why would one method be preferable over the other ? Are there significant advantages to reversing a lens directly to the camera body ? As far as magnification goes, which technique gives better results ?

[SkipD]

I used to use a fitting that would let me reverse the majority of my old Nikon F lenses - circa 1967. The fitting had a male bayonet fitting on one side that would go to the camera body and a 52mm thread on the other side that would screw into the filter threads on a lens. This rig worked great for extreme closeups. It did, of course, require either the Photomic head (a meter attachment that replaced the standard pentaprism) or a lot of experimentation with offsets to meter readings.

I had never heard of reversing two lenses together until quite recently. The only reason I can think of why that might be better is to be able to use the camera's auto focus and exposure features. If there's another reason to use two lenses together, I would like to learn about it.