Thanks for all the comments.

After thinking about this it occurs to me that I USUALLY am not on the larger sprockets when I shift down to the small ring (I typically do some RD shifting before the big-small shift). But USUALLY I don't drop a chain. I would not be at all surprised to find that every chain drop that I have encountered happened when doing a FD shift in the larger rear sprockets. So caution there is step #1 .

dave