Well, I reprieved my 35XL having been told that using a CF would make it useable for my needs and, now it has arrived, I took the opportunity of time and weather today to test it.
As is always the case with these things, I got inconsistent results and will have to go back and check my methodology. In particular, in one 9 stitcher, there must have been some camera movement though I can't see how, because stuff just didn't line up well. Then in two three frame horizontal stitches (12 left, centre, 12 right) I seemed to get better correction on the right in one attempt and on the left in the other.
I also got some really weird white balance effects, despite setting everything to daylight and double checking in post. in the nine-stitcher, the centre frame LCC had a green bias, the four corners had a blue bias, and the centre rise and fall frames had a more neutral look. There was no procedural mistake here either, so this was really odd.
Speed is of course vital and I am now going to go to a process of shooting the 'real frames first, in quick succession so that the light doesn't change, followed by doing the LCC frames.
But the good news AFAIAC is that the thing I most want, reasonably well corrected rise, seems possible. The following two shots are:
first, no movements, CF, LCC applied but light falloff correction reduced to 50%. Then, exactly the same but with 10mm rise.
I would be interested if those with very good colour vision have an opinion!