Hi, I agree with your comments that BPNDX and BPSPX are not too useful. My reasoning is that they are large caps and tend to move together, thus a high figure can exist close to the beginning of an upmove.
BPCOMPQ however contains many small fry and is more likely to reach a higher value towards the end of a run. I only partially agree that you need to wait for a turndown, history shows that most times just a high level of BPCOMPQ means that a top is nearby. But as Zeev says, dont rely on one indicator, an use stops. Then when you get an excpetion to "most times" you are OK.
I would like to learn how BPCOMPQ and BPOTC differ? Do they have different components? If BPOTC has a larger number of small fry then I think it might be a better on e to use.