per RGB:
I think it is a losing crusade to try to convince people that a common sheet bend does not include a loop that nips
Not at all.
Very careful use of language is essential.
Terms:
[ ] Nipping loop = a closed helix that is loaded at both ends. It may have left-hand (S twist) or right-hand (Z twist) chirality.
In #1431 Sheet bend there is no structure that matches this definition.
You have constructed the phrase 'a loop that nips' - which is different to 'nipping loop'.
In a Sheet bend (which is an end-to-end joining knot)
an SPart traps and crushes 'down' upon its own tail (ie 'down' referring to force acting from one side). This action of trapping and crushing its own tail is a completely different operation compared to a 'nipping loop' within an 'eye knot'.
Your use of the phrase 'a loop that nips' is conditional and is one way of trying to describe the action of an SPart crushing 'down' upon and trapping its own tail.
In a #1010 Bowline (which is an eye knot),
the SPart does not trap and crush a tail. The SPart morphs into a 'nipping loop' - which then fully
encircles and crushes both legs of the
collar (which collectively is a 'bight structure'). And in this case, the nipping loop is loaded at both ends.
NautiKnots ties his nipping loops (sorry Mark) with Z chirality, whereas in Z-laid rope I prefer to tie with them with S chirality
This 'preference' toward Z or S twist is often times linked to whether a person is left or right handed -
and; how you originally learned to tie a Bowline or a Sheet bend. Right handed knot tyers will usually form a Z twist nipping loop (I say usually, but there are exceptions...and again, influenced from whom you learned how to tie it). Whether a person ties a common #1010 Bowline with a Z twist or an S twist makes no difference to performance of the eye knot.
As to differences between #1010 Bowline and #1034 1/2 Bowline - we know that the latter is resistant to 'ring loading'.
In a head-to-head MBS yield (ie pull-it-to-failure) test, I think the matter has not been investigated to any degree of scientific rigor by an accredited, certified test lab. I am not even sure of any 'backyard testers' who have tried to construct a
repeatable test that has been properly peer reviewed.
In the case of comparing #1431 Sheet bend (tails same side) to #1432 (tails opposite) - we must keep in perspective that these are 'end-to-end' joining knots..they are not 'eye knots'.
It may be a useful analogy to look at how wire rope grips are oriented on steel cable to form an 'eye'. There is a right way and a wrong way of orienting a cable grip.
In the same analogy, it is always advanced that #1431 is more secure and stable compared to its cousin #1432.