I don't think that the direction of the eye has any effect on the hooking ability of the fly, ie, the so called "hooking or penetration angle". Take a look at pg. 178 of Designing Trout Flies by Gary A. Borger. The angle of a hook eye has no effect on the angle of pull on the hook.
It was once thought that down eyed hooks had a better "hooking angle" because the down eye was thought to create a downward pull on the hook, and that this downward pull would "bury" the hook. Apparently this belief still continues and it is untrue. Mustad has an example of a hook penetrating a foam block that presumes to show the importance of the angle of the eye but this is wrong for reasons discussed below.
The first point is that the angle of pull is actually determined by the position of the hook in relationship to the tip of the rod and not the angle of the hook eye. Also the strike occurs when the fishes mouth is closed on the fly which places the hook in direct contact with the mouth of the fish.
Secondly, once the point of the hook enters the flesh of the fish, all angles of pull will bury the hook because the bend of the hook causes the point hook to rotate down into the fish, which then buries the hook until it the bend of the hook causes the hook point to rotate out of the flesh.
I also once believed that penetration angle was important, but as I read more, I've changed my view. Therefore, I have some disagreement with what Mustad has written about how important the eye position is in hooking. I think any effect is very very minor. The reason is that hooking angle does not stay constant as the hook on foam block illustration would suggest. A foam block is not flesh. Flesh is dynamic and deforms in response to penetration. A foam block does not.
Once the hook point penetrates flesh, the hook pulls on the flesh deforming it and simultaneously the hook rotates in line with the angle of pull of the line. The eye of the hook no longer rests nicely at a 90 degree angle to the flesh as it does on the foam block.
The angle of pull on the shank and the hook point are pretty much equal when the hook eye does not rest on the block. I believe that this angle of pull drives the hook point further into the flesh at pretty much the same angle which is determined by the angle of pull on the eye rather than the angle of the eye of the hook.
So the slight offset of the up or down eye from the straight eye really makes no difference on hookability. What does make a difference is the sharpness of the hook point and whether the hook gap is limited and the whether the hook point is offset.
If the hook point is sharp, I don't think eye position matters much. The hook point will enter the flesh regardless of the difference in hook eye position. Hooking gap and offset have a greater effect in my view because they affect the probability that any fish flesh comes to lie against the hook point.
I think hook eye postion is more about the aesthetics of the fly and the ease of tying the fly than any effectiveness in hooking.
For the same reasons, the type of knot makes no difference on how the well the hook will impale the fish. It does make a difference on manipulation of the fly such as the making a surface fly skate but as to hooking fish, all knots are equal. Once the point enters the flesh, all knots will rotate the hook into the fish.
Some fishers also think that a down eye hook somehow "narrows" the hooking gap and negatively affects the hooking ability of the pattern. That is not true either. The gap is the distance between the hook shank and the point and is not determined by the direction of the eye. What narrows the hooking gap is the material that is tied onto the hook at the location of the gap.
So the direction of the eye is not a significant factor in hookability of the pattern.
For the best hooking ability in midge patterns, a 2X short hook with a relatively wide gap for hook length and an offset point (gap) will improving hooking compared to a standard hook with no offset.
