Beyond their good level functionality, one other reason for which these figure eight based tangles drew my attention, whereupon being planted in this thread, is that they are topologically equivalent to crossing knot link knots, bowlines or not, fitting in this current knot assemblage.
Verily, getting back in the main subject and aligning with the title of this thread, two knot structures are illustrated here, in a loose and tight form, directly originated from the previous figure eight based instances, with two consecutive tugs of the on going eye leg and its continuation cords, in both knots.
The first knot is a bowline, with a simple helical S nipping loop, having three rope diameters in it, topologically equivalent to the figure eight based pseudo bowline, posted at reply#13. The relatively effortless yielding of the two collars after intense streching/loading events, decompresses the strain accumulated in the nipping loop, therefore boosting its jam resistance.
The second knot, is topologically equivalent to the enhanced figure eight based 1051 knot, posted at reply#10, hence by extension not a bowline, with two rope diameters in its nip, but also very easy to untie.
If i was to pinpoint some drawbacks, i would comment that these closely related two collar TIB knots, have not the best ring loading profiles, but sufficient if properly dressed and cinched, plus their nubs, do not line up properly with the eye of both knots. Beyond the aesthetics, it is this very transformation process that causes this shifting to the axis of knot symmetry, which together with the crossing factor may induce some deformation, if the knots are subjected to high tensile forces. Moreover, the simple helical nipping loop constitutes detterent the development of a reverse loading profile, hence there would be no EEL qualification in this geometry.