Laurent,
I really don't think McMann survived. If you look at the official documents:
He is currently listed on the "official" MIA list:
http://www.dpaa.mil/OurMissing/World...spx?br=aaf&a=m
He is listed as MIA on the ABM website:
http://www.abmc.gov/search-abmc-buri...5#.VXgTrlYViko
He is listed with a FOD (finding of death) on the official NARA list for Colorado:
http://media.nara.gov/media/images/28/26/28-2577a.gif
http://warmemorial.us/mediawiki3/ind...%281LT%29_WWII
As for Rich, as you note there is no POW record for him. Here is his obit:
http://www.deseretnews.com/article/8...ch.html?pg=all
It seems to say he was shot down once and spent a short time in the water. No mention of a date when that happened, but note there is no mention of being a POW which these obits usually do, if it happened.
It may be that one of the first book authors got it wrong regarding McMann and the other authors just followed his "lead". It is all rather confusing, but I do think the official documents are more likely to be correct.