Both the original and new versions of the Micro Converters support 3G SDI (Levels A and B) even though only the new model is labeled 3G. On the HDMI to SDI Micro Converters, there is an option in the Converters Setup software (via USB connection to a computer) to set the 3G SDI output level to either A or B. On the SDI to HDMI Micro Converters, both 3G SDI levels are accepted on input.
The main new features of the Micro Converter 3G models over the original versions are:
- Support for 1080p47.95 & 1080p48 frame rates (high frame rate variants of 24 fps for film)
- Support 2K DCI resolution video (2048 x 1080) at various frame rates (from 23.98 up to 60 fps)
- Support HDMI to SDI timecode conversion (the original converters did not support HDMI timecode)
- Support for 3D LUTs on the SDI to HDMI 3G model (useful for color correction or monitoring log video signals)
- USB-C port for power (rather than micro USB)
There have been some recent firmware updates for the Micro Converter 3G models specifically, so I assume this means that there are some internal differences in the hardware of the new models to enable these additional features.