Warning: I haven't read the entire thread, and I am strictly an amateur...
I shoot mostly VR spherical panoramas using the Nikon 10.5 FE lens, where the right head (NN3 in my case) and correct setup are essential. Which is not what the op was asking about. But I also shoot single and multi row landscape panos. I have found that having the NPP/camera set up correctly, or even roughly correctly (I sometimes use zooms and only know approximately where the NPP is at differing focal lengths), helps a great deal where there is a pronounced combination of foreground and distant features: the greater the separations, the worse the parallax. To some extent, without a panohead, how well the stitch/blend works is dependent on exactly where on the subject the joins fall. I am using PTGui to stitch (excellent product) in combination with its own blend code, or Enblend or Smartblend. These usually give very similar results but occasionally one may be marginally and unpredictably better.
A point that may not have been mentioned (or I have missed) is that most people shoot panos in portrait format to maximise final resolution. For most regular non-panoramic heads this would mean that the POV/NPP swings though an arc. I haven't tried this but it doesn't sound too promising to me! It's worth mentioning in passing - I hope I'm not insulting anyone's intelligence - that in stitched cylindrical panoramas, horizontal elements (+ or - zero degrees of pitch) will exhibit unavoidable curvature which becomes more pronounced as pitch values increase (or decrease).
The NN series of panheads are small and light and if not perfect, they are not too expensive either.