I mirror my roamio to two displas. A 1080P projector, and a 1366 X 768 plasma. my avr's don't offer scaling features so my displays are fed pure signals from TiVo. My findings are that 1080i content looks better outpit at 1080p when viewed on my 1080 projector. because of this result I was also hoping 720P content would look just as good on my 720p plasma when the TiVo was set to output 1080P fixed. this would be good because then I wouldn't worry about time out for resolution changes when changing channels. unfortunately after more testing, 720 P material still looks better output of TiVo at 720 P when out put to my 720p plasma. 1080p playback doesn't seem quite as soon as smooth. Like less frame rate. so I'm glad series 5 tivo has1080 P 60 fps, its just too bad 1080 P output doesn't look as good as 720 P output on my 720 display. end result is I have the following 3 rez outputs in settings checked :
-1080P 24 Fps pass through.
Ill do some more critical testing of 1080p 24 FPS later, but I presume if you have a display that correctly handles pull-down such 24fps films such as on Netflix, then its better to enable this.