X1 Anyroom DVR with Xi3, Xi5 or Xi6 Box

I current have a TiVo echo system and know my days are numbered (currently trying to get a cable card repaired/replaced after a firmware upgrade bricked the one I been using for 10 years).  Trying to figure out a plan B and have a few questions that I can seem to find the answers to after searching this forum and Reddit.

I current own my own Netgear Nighthawk Modem (xfinity approved) and Wi-Fi router.  

If I switch to a X1 DVR (main room)  and X1 NON-DVR HDMI ONLY (Xi5 or Xi6) in the other rooms, do the Xi5 or Xi6 have access to the local DVR recordings? Similar to the way the TiVo Minis are a extension of the main DVR.

I have seen only one or two posts that claim the X1 NON-DVR HDMI ONLY (Xi5 or Xi6) only access recordings from Cloud DVR.  I also understand that as of a few years ago that customers can now use their own customer owned gateway/modem, so that isn’t a problem.

Appreciate any clarification on how/what DVR recordings the wireless boxes have access to.