That is a really good tip. Thanks for that!
Yeah, I work at an art museum and used to stitch all the time, working with a D700. I would of course never
have enough resolution, so it became a matter of some urgency to streamline the process.
So I found that if I set up the shot with, say, a 50mm, I could just switch to a longer lens without moving anything in the setup, and do 6-10 segments. The segments will then align perfectly with an upsampled guide shot used as a base for the merge (since the total angle of view is the same), and it also eliminates the need for further geometry adjustment. The trick is to upsample to a slightly smaller size than the merge would normally end up at, so that the merge process only samples down, not up.
The rotation point has to be set up for the long lens in advance.
And then of course I got the D800 and all of this was no longer needed. The results I get now are just as crisp at the same resolution, as long as I use live view focusing, mirror up and all that.
Using strip soft boxes, or even umbrellas, together with polarizing film is something I haven't tried, but it sounds like it's worth some experimenting. The "dead metal" effect (particularly in frames) I have just taken for granted as an unavoidable side effect.