Short answer: no, I haven't used either of those apps.
I have two panorama apps, and both auto-snap, though I wish they had the option to manually snap, or at least give better warning that they're about to snap. Otherwise, how do you avoid snapping photos while the camera's moving?
My panorama apps are Photosynth and DMD Panorama; I got the latter on a one-day-free sale, otherwise I wouldn't have been compelled to spend the $1.99. It does create some nice panoramas, but partly because it really restricts operation; you have to hold it very close to vertical in portrait mode or it won't take the shot. Resulting photos all seem to be 1300 pixels high (out of 3264 vertical resolution).
Photosynth does not have this restriction, AND it has an option to lock exposure -- VERY important in a panorama photo, especially outdoors, because the lighting will almost certainly be different from frame to frame. I would definitely try it out, especially since it's free.
I can't say about resulting pixel count of photos in Photosynth; I don't have a photo at hand, and the way it overlaps, it would be kind of hard to determine.
Regards,
Tom
Added later: Did a little testing with Photosynth. I held the camera in portrait mode and took a horizontal panorama (as per constraint of DMD Panorama). The vertical resolution was ~725 pixels, compared to 1300 for DMD. So, I think DMD wins here. Also, DMD trims the rounded tops and bottoms of each frame, so the final picture is more aesthetically pleasing (a true rectangle). If you want more pixels, and you can live with the constraints (and without the $1.99), DMD might be a better choice over Photosynth.
Added even later: Hey, guess what I found out DMD Panorama has? Exposure lock. Naturally I didn't see it because it was right on the screen in front of me! (It's just like the flash setting, which I tend to ignore.) And, even better than Photosynth, you can either pre-lock it, or let it lock on the settings it chooses in the first frame.
