Here is my understanding. Your ADS-B out signal has to match the FAA performance standards if it is not TSO'd and you are EAB or ELSA. However, let me share my experience.
I installed a TSO'd FreeFlight XVR-978 transceiver in my ELSA. I got a compliance report from the FAA revealing an ICAO hexiidecimal ID issue and a BDELT deviation. In plain English I screwed up the ICAO identifier when I entered it into the unit and my ADS-B out was reporting glitches in my vertical speed about 0.3% of the time. I fixed the ICAO code issue,but the BDELT issue persisted at the 0.3% rate, so I contacted FreeFlight and Dynon who said anything less than 1% was OK. Next I asked the FAA guy what the FAA spec was for BDELT error, and it's been three weeks with nothing but crickets --- I guess it's true, we're not happy until you're not happy.