Guide and (we think) Live TV comes directly from the database. So in XBMC you want the the myth:// URL to point to the Master Backend as that's where the DB is, 192.168.1.132.
Playing of recordings can fail if the IP Address is configured in MythTV incorrectly. See
http://wiki.xbmc.org/?title=MythTV#Setup_in_MythTV
I don't know how the Slave would interfere though. If recording is being done on both, are there physical recordings on two different machines
If so, cmyth may not deal with that. I'd try setting the Local Backend IP Address on the Slave Machine to 192.168.1.190 rather than 127.0.0.1.
Do you need two MythTV backends running? I believe that is normally only done if you want to record a LOT of channels at once and can't physically do that on one machine, or if you want to offload transcoding work or commercial flagging etc. to another machine.
If you can do all the recording you need from one box, then perhaps.
1) Setup one machine to have MythBackend installed. (Machine 192.168.1.132). Ensure that the mythtv-setup -> General -> Local Backend -> IP Address is set to 192.168.1.132
2) Install Myth Frontend Only on the other machine. Use this to test that playing Live TV and Recordings works (Machine 192.168.1.190). You don't need to install full MythTV if you just need to watch Live TV or Recordings.
3) Install XBMC on 192.168.1.190. myth://user:
[email protected]
The old xbmcmythtv script used to start "Live TV" by scheduling a Tuner for a period of time (default was 120 minutes I think - could be changed through configuration). MythBox probably does something similar since it was forked from that code.
I believe the myth:// protocol does something different, so should be better at releasing tuners when XBMC is closed and the Myth Client is closed.
Check the mythbackend.log file to see what is going on.
Regarding the Tuner status issue after suspend. That is likely not related to XBMC. I recall that coming up as an issue for Tuners and Myth TV in general. Some cards support Suspend, some not. Try and find out if the cards you are using support it, or if there are any tweaks needed to Linux config to allow it.
On my Myth Box, I have it shutdown fully when not in use to avoid that whole issue.