I really did think that the hex shape was a newer design. At a couple of local intersections where the dissimilar loops exist and don't overlap well, I tend to get frustrated as to which is which and either run the light or walk over and push the button. Or a car comes along... so my application of scientific method to see exactly what works... has been pretty slim.

Where single well defined loops exist, I can often trigger those with little problem. But I do know of some that just don't detect cyclists. My neighbor rides a motor cycle and one morning we both sat at one of those odd double loop (old and new) locations and he looked to me and said, "about half the time I get it to work." We both shook our heads and laughed.