Honestly, HBD APR has been in the ''too good to be true'' category for a while. And as @elmerlin said the other day in a discord room (ocdb I guess) it's not about ''being able to pay that 20% APR in a sustainable way (because for now, it is!), it's more about balancing incentives''
And I can't agree more on that.
Hive Power holders should be the #1st class citizens on the Hive chain, and 12% for HBD savings feels more than reasonable (at least to avoid eclipsing the APR of HP).
On the other hand, I believe that as a community we should be careful about changing the economic rules of our chain. Money is skittish and does not like unforeseen changes. Be careful there is imperative not to change the numbers too often.
I have been thinking about a hypothetical way to adjust the % interest on savings that might be interesting, but that is a topic for another day.
I also agree with the points of @deathwing to make HP more appealing, I also believe that reducing a bit posting rewards for an increase in HP APR would be a good measure.
Of course, I own a lot of HIVE, so my opinion is hugely biased. I'll change the params of my witness to signal 12% APR on savings.
Have a good day @gtg !