Are there any standards for testing I should be using or are comparative tests preferred ?
It is like you find a man suffering from dehydration in the middle the desert, and you ask him if he prefers tap or carbonated water... ANY test is better than NO test. Even simple, tug-of-war kind of testing two different bends tied on the same line or loop to see which one slips or breaks more times than the other, is most welcomed. To just have an idea about tests on knots by other people before you start your own, have a quick look at (1).
If you want to test different bends against a "standard" bend / benchmark, you may choose the ( most symmetric forms of the ) rethreaded overhand or fig. knots, the Fisherman s knot, or the Zeppelin bend.
Regarding the knot being difficult to untie, I find that to be true of the variation where the working ends are pointing in different directions but not true where they are parallel and can be used to pull up while pushing down on to loosen the knot.
I know only this : to quantify and test how easy is to untie a knot, is the most difficult thing one can even think he can do !
I have no idea about which of the two forms of the knot, or which of the two knots, is really easier to untie after heavy steady or alternating loading, on various materials, et... Ashley says that the DH bend "
with parallel ends" ( ? ? ? - the tails are parallel in
both bends ! ) "
appears to be preferable", but, although he says this right after mentioning that the DH bend and the SH bend are "
exceedingly hard to untie", he is (once more... ) not clear on what he really means. Personally, I prefer the "balanced", more symmetric form, and I would be ready to turn a blind eye in a small, insignificant difference between the two. The Double Harness bend with tails pointing to opposite directions is a most beautiful thing - the "other one" looks like...well, certainly it looks like all the "similar" bends "with parallel ends"... In general, to my eyes, in bends the best thing is Tail ends parallel to the Standing ends and the axis of the knot. The next best thing is Tails symmetrically placed in relation to the axis of the knot. At the very last place, is tails leaving the knot from the same side, and towards the same direction.
( I am the last person in the World to have a say about tests of knots - my speciality is blah-blahing...but there are other members of this Forum who can enlighten you with their knowledge and experience on this matter.)
1.
http://www.paci.com.au/downloads_public/knots/14_Report_hitches_PBavaresco.pdf