Until told otherwise, or a new update, it appears Collector just is not setup to collect high accurcay GPS data, even if you can connect to a bluetooth GPS receiver. It does not store a Z elevation even if the feature is z enabled, and it does not store PDOP, horizontal, vertical precision values typically associated with High accuracy GPS. I am hoping someone from ESRI can clarify, and or provide a status update on better support for RTK GPS in hopefully the upcoming release of Collector.
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