Sorry I'm late to the conversation. From what I have learned so far about eye splices, the main purpose to use a Brummel is to lock the splice in place during times when there is no load on the rope. If you are going to lock the splice with stitching, then the Brummel is not needed and needlessly degrades the rope strength. During times when the rope is loaded, the load will hold the splice in place. So a straight bury has higher strength than a Brummel, but still needs extra stitching to lock the splice in place. It doesn't need to be a lot of stitching, since it is only for situations with no load on the rope.
Ok, now that I got that off my chest, I have an idea to run past you guys.
Assumptions that I will believe are true:
1) The weak point of the whoopie sling is at the adjustable bury on the side of the tail exit. This makes sense because the loop on the other side effectively divides the forces over both halves of the loop, while the tail holds no load, so the single line takes the whole load by itself.
2) Degradation in rope strength is caused by bending and tight curves in the rope. The higher the degree of bend away from straight 180 degrees, the higher the loss of strength. This is why tapering helps, it forces the fibers of the sheath to form a more shallow bend and there fore conserving more strength.
If both of those are true, then, the way I see it, the only way to make the whoopie sling for any given rope stronger is to add a buried taper inside the single line with the wide end starting just where the tail exits the adjustable bury and tapering down inside the single line. This would help to simulate the taper that would be there if the sling where not adjustable and the loop was just buried with a taper at the end. With this new fixed taper, you can have it both ways, you can have an adjustable bury AND a taper to help with strength conservation.
So what do you think? It should make the sling stronger and would reopen the debate as to where the weakest point would be, in the adjustable bury or the fixed eye bury.