Running thru the TV you will lose lossless codecs like Dolby TrueHD and DTS HDMA, etc., but if all you're running is dvd, then that's not an issue since they don't have lossless codecs. Some tvs will pass back only 2.0 rather than 5.1 via ARC or optical, too (and generally not much difference between hdmi ARC and toslink, altho I think I've seen some claim hdmi ARC will handle DD+ with Atmos whereas I don't believe that can pass thru optical but not sure since I don't have an Atmos system).
My main purpose of an avr is audio, not video, and I just pass video thru the avr anyways (rather than use any video processing in the avr)....never really tried the tv at all as a switching center. HDMI should pass thru units cleanly, tho. Or are you worried about video game lag or something?