I stitch in the 6X12 format using just a RRS PCL-1 and L bracket on a ballhead. The reason I need the PCL-1 is simply that for vertical pano's it's much easier to flop the ballhead over, attach the PCL-1 and then put the camera on horizontally using the side of the L bracket giving positioning for the maximum amount of resolution for a vertical.
My current stitching work is here www.studio-beni.net/jerusalem
, I've never once seen parallex error and sold the nodal slide that came with the setup. I only use rectilinear stitching using Autopano Pro. I use the vanishing point tools to correct the verticals. I will readily accept that I am probably doing quite a bit more 'stretching of pixels' in software due to not using the nodal slide and not using rise on for example a t/s lens however with 35+ megapixels at a minimum I've got plenty resolution to spare to be honest. Prefer not to faff around when shooting. I'd quite happily shoot just using the pan base of the ballhead if shooting horizontals, I know the software is more than up to the job. Autopano seems to be much better for this than PTGUI. From what I've read PTGUI is far more particular about needing nodal point shooting.
Of course if your camera is not fully 'squared off' then you will get gaps at the edges due to the curvature of the panning movement. Simplest solution is just to shoot a row of frames at the sides where the curve will occur (top/bottom for horizontal, sides for vertical). Far better than having to sacrifice composition for a completely levelled setup. Again as I've never found Autopano not to automatically correct the lack of nodal slide I'm far happier shooting a multi layer (which is what the above is in effect) with just the ballhead and PCL-1. The RRS multi row setup looks unstable at best. I have little doubt that even stretching the pixels I get sharper results not using that ridiculous off centre setup dangling 8 inches above the ball head.
It is far easier to compose when you have a specific ratio you are shooting with. I compose with a 50mm using the grid lines of the (accessory) screen in my 5D then attach a 100mm and shoot the same FOV but using stitching. I specifically use a 50mm because that is the perspective I'm trying to achieve. Eventhough I use a 100mm to shoot with, as the FOV and distance is the same the actual final perspective is that of the 50mm I framed with originally.
What I would like is a better solution than the PCL-1. The pano tightening screw is tiny, interferes with the big knob for tightening the plate and in general is very hard to lock down when you have a heavy lens attached. Doing the below pano with a 70-200L and multi row was not fun in the slightest, I don't have strong fingers and trying to tighten that tiny knob with the big knob in the way and the huge lens pulling downwards (it was in vertical) was not fun. I know most of the time people are not stitching in vertical so it wouldn't be an issue but the RRS multi row setup specifically has the PCL-1 in vertical as I use it and it isn't user friendly.
60 Megapixels, multi row, using ballhead pano base for horitzontal and PCL-1 for vertical, no nodal, no problems. I know all the theory but I'm out there shooting it in practise and it just ain't a problem. Alain Briot found exactly the same thing and he uses the unsophisticated PS stitching tool. He also doesn't bother with the nodal slide. Flame suit on...