Alan, there's ample evidence that some manufacturers systematically exaggerated coverage. The best catalog claims can do is set an upper bound. The older a catalog is, the more likely it is to mislead. Modern claims backed up by MTF curves are credible, old ones aren't.
You're right, anecdotal information is very hard to evaluate. Unfortunately so are the claims made in sales material.
I know that you've corresponded with Eric, he's mentioned you to me.
To move this discussion to another, less personally painful field, I know an aquarist who decided to compile a list of validly-published names of fishes in a group. Who and what the group is don't matter. He worked hard, did a lot of well-done bibliographic digging, published list after list after list. I thought it was a waste. Having a fish (in the group, of course) in one hand and a list of names in the other with no way of matching struck me as useless. Having a fish in hand with a name on the list attached with no way of telling whether the name fit also seemed useless.
To get back to cases, making an uncritical compilation of marketing claims is probably great fun but something more informative would be more useful.