I thought a great indicator had been found in British Bulls, but I see one major problem. It is not tracking what we generally have: It tracks paper, we have gold.
All the advice I've seen posted on the net of late, especially with the suspected disconnect between paper prices and physical gold (& silver) prices, is to ditch paper and get physical. If folk follow that advice, it follows that the ETFs will take a hit and BB may correctly forecast a bear phase on its terms but which is not realised (or very transiently realised) in the physical market.
Then again, I saw somewhere that the ETFs had only retreated by 11% of their holdings in the last correction, so I suppose they still have a major influence on the market price.