The question is, if any technical or economic risks emerged as a result of continuous 20% APR. I don't see any. I agree with your assessment that when Hive price isn't moving upwards for a while it may seem as though HP isn't earning as much HBD. This may imply some kind of competition. However, regardless the ROI optics Strong Hive and HBD only benefit each other.

Given that there is no evidence of any imminent risk to the chain, community, or economics decreasing the APR wouldn't be a good idea. Because this will result in break in consistency, and creates uncertainty in HBD as savings investment.

I do believe 20% APR eventually would produce its results, but not until after next bitcoin ATH when profit takers look for stablecoin options.

GTG has set a target to gradually lower APR to 10%. That means 19% is only temporary.