Bluetooth remains an 'unusually painful' technology after two decades
I do not know if this is true, but I read somewhere long ago that Bluetooth was intentionally designed to be complex to create a high barrier to entry for companies implementing wireless data, particularly in the phone industry but perhaps to make things like peer-to-peer protocols difficult to implement reliably also.  ANT+ is certainly much easier to use and more stable.  The Bluetooth spec in its entirety is up to what now, 3000-5000 pages?  Do you have a year to read it and understand it before starting your project?  And all the Bluetooth vendors have created their own custom stacks with incompatible API's "designed to make using Bluetooth easier" but also ensuring that it is difficult to switch vendors and making it difficult to do anything custom (first you have to reverse engineer their API, then guess what is inside their proprietary firmware stack).  I've heard the same things about the SD card standard.