My two cents... As to the original question about whether PT Gui Pro can correct for vignetting, I'm pretty sure it can. One trick is to give it a full 360 degree row of pictures to work on so that it can figure out the corrections needed for a successful blend, and then you can apply those corrections to the original files. Otherwise, I believe, you have to enter figures numerically as you would with its ancestor, Pano Tools. Check this tutorial for more and better information:http://www.ptgui.com/examples/vigntutorial.html
I should add that I do not practise what I just preached. If I need to make corrections to an individual file, I find it much easier to use ACR or a Photoshop plug-in like PT Lens ( http://epaperpress.com/ptlens/
Regarding a later posting showing blending problems with PT Gui, I was surprised to see it. PT Gui has always impressed me with its ability to smoothly blend seemingly impossible variations in the density of joined edges. (I'll propose a radical notion about that in a moment.)
I have tried AutoPano Pro and PT Gui Pro, but now use PT Gui almost exclusively. First, because it runs on my Windows machine easily five times faster than the other, even when using the Smartblend plug-in. Second, I was just never able to figure out how to manipulate the control points in AutoPano. I'm sure that's more my fault than the software's--I need to read the directions better. But the program takes a very long time to redraw previews after corrections are entered, and I lose track of how my entries affect the result.
AutoPano strongly markets its ability to find relevant files in a folder and organize them for stitching. But even that process, fun as it is to watch, is terribly time-consuming. It's really not a big deal to drag and drop your files right out of Bridge or other browser into PT Gui.
Regarding hardware, I am a big fan of Nodal Ninja. The price is reasonable, the quality is high, and the manufacturers are very helpful. I'm sure the RRS devices are very good too, like their other products. But the Nodal Ninja is cheaper and fits into one small elegant case. It's dedicated to the one purpose of panorama shooting, so you can set it once for your body-and-lens combination and (almost) forget about it.
If you've stuck with me this far, well that's your own fault, but here's my ridiculous idea. The premise: exposure settings for panoramics are supposed to be locked on manual, shot in raw, and widely bracketed to help with brightness differences or, shudder, HDR. (I shudder at HDR only because I still can't make any sense of it. But that's my burden and a story for another day.) The proposition: if we're going to bracket raw files anyway, why not shoot with the camera set on aperture-priority automatic? Ignoring new-fangled settings like evaluative metering and such for the moment, plain old auto exposure will create a series of files of middle value tonality. They will very likely be too light or dark for certain parts of our scene, but because they are putting our subjects into the middle of the tonal range, they should be very "editable". (I really need to find out if that's a real word.) We still have bracketing to cover our back, and we still have the option of raw editing to help us even more. Then we have what I mentioned earlier, the observation that got me started on this idea: the nearly supernatural ability of current stitching programs to smooth out exposure variations.
You'd think I would just go out and test my own idea, but I only thought of it the other day and haven't shot any panoramics since. So I will rephrase it in the form of a question: Have any of you shot your panoramics on automatic exposure, and how did it work compared to fixed-manual?
Oh, one last thing. The best information I have found online about this whole area has been in tutorials written by John Houghton. http://www.johnhpanos.com/
He uses PT Gui, but I bet you'll find plenty of good information even if you don't.
If you want to see stuff I've been doing: http://www.michaelbaileyphoto.com/panos.htm