I have read this post all the way through and agree its got us all thinking. I have found titanium sensors reading either way but have not the memory to write about which ones were different.
What I will say and have always try to do is beleive nothing what you here and half what you see. In otherwords beleive what you can test and prove yourself.
I will be checking lots of these in the future but its no good through live data as in broadband sensors it does not give you the real figure only a simulated one that sometimes equates to an ordinary lambda sensor although broadband is fitted.