Hi Art,
Not taking any issue with your statement about wearing a whistle on a neck lanyard, just making an observation that I've been wearing a Fox 40 glow in the dark whistle plus an ARC AAA lug style light for years and have not had any issues.
The only time I've really thought about it when I wasn't needing to use it is when I was laying down or other reclining position and it moved a bit.
Having it quickly at hand has been well worth the (IMO) very minor discomforts (hardly any at all really). Believing in redundancy, I also have a STORM whistle in dayglo orange that lives in another kit that is close by most of the time, as well as other items that back up the back up items...
Here is a reference to an older thread that discussed whistles and a few other things from several years ago.
http://forums.equipped.org/ubbthreads.php?ubb=showflat&Main=2500&Number=18520#Post18520Thread titled Why a whistle is important from several years ago. There were several other related discussion threads.
I agree with the old saying about the pebble in your boot.
EDITED: This link seems to take you to the end of this rather lengthy thread, be sure to scroll up to the top and start reading from the beginning for more info.
Regards,
Comanche7