I had 2 TVs connected over coax via the composite output (3 RCA jacks) at home. Usable but the pictures weren't the best. Changed the kitchen one to HDMI over coax with significant pic quality improvement.
The pic/sound is delayed (a little less on the HDMI TV). The great room and kitchen TVs are open and close and the sound delay is annoying so the kitchen sound is turned down. This should not be a issue with a outside RV TV but may be with multiple inside TVs.
I'm sure the delay occurs in the receiver outputs and not the converters.