Several have suggested multiple EPG sources to address the issue of certain channels being fed by different time zones. Potentially one could then assign the time-zone off channels to a separate tuner OR have the ability to set different sources for different channels. Another option (but less flexible) would be the ability to lock to an single EPG (as it is now), but have a time-shift per channel option.
In any case, some solution here would be really nice, because at least in my case (using HDHomeRun Premium service), DVR is working about 50% of time because of time zone issues.