I've had a panoramic head for a while now, but asides from some test shots I've never actually used it in the field until the other day. I didn't even bring it over to NZ with me originally (I got my parents to mail it across for me last week.) It is a cheap ABS and aluminum head, not one of the expensive Manfrottos or RRS heads. When I bought it I wanted to try out some stitching without investing a lot of money.
My theory was that I could phase out the 6x17 stuff I was shooting and replace that with digital. I don't see stitching as a viable solution for replacing 4x5 (I like the movements of my 4x5 camera, and having to shoot several row panoramics seems to be more effort than it's worth).
Anyway, the head arrived the other day from Oz so I pulled it out and took some actual images in the field. Here are my initial conclusions:
First generation capture - no need to lose quality when scanning film
Cheap when compared to film
No Lab fees
Instant feedback on exposure (no worrying about if the Grad ND is in the right spot, or if that shadow will block up)
Great quality files with large dynamic range
The head I'm using needs the camera to be bolted on - this ties up my digital camera. I usually like to have my 4x5 set up and have my digital around my neck so I can snap digital images as proofs.
I prefer the look of scanned film at large magnifications - personal thing I guess. Most digital photographers would probably call it noisy/grainy/soft but I prefer the look.
The head I've got is pretty flimsy - I wouldn't use it with a lens longer than say 100mm
I have yet to have much success in getting satisfactory stitches with scenes that include moving elements (like waves in the ocean). Given I shoot a lot of oceanscapes this is a big limiting factor for me.
Hard to envisage the end image - because you're shooting individual images it is difficult to know what will be in frame once everything is warped and stitched. Solution for this is just to shoot loose, but this means taking more images and more time.