I use wall plates for everything except for HDMI (receiver to projector) and for Cat6 for HDMI-net Extenders (Cat6 is box to box).
The projector has two HDMI inputs, from two different locations. Both are fed with "redmere directional cables". Location 1 is from the receiver and is direct. Location 2 is in a pole by the couch (So I can use a laptop with projector), that location is terminated with a wall plate and the few times I have used it, it has worked fine.
HDMI to me is problematic. My Blu-Ray player goes to receiver, and then receiver to projector; playing 3-D was fine, now lately the Blu-Ray player doesn't sense a 3-D display device and refuses to play the discs. It drives me crazy.
Projector: Epson Home Cinema 5030UB
Receiver: Pioneer Elite VSX-90
Bluray: Sony BDPS5500
Screen: Elite Screens ezFrame Series, 100" 16:9 AT AcousticPro1080P3 FF Screen
+ 6 Sonos Connects, Dayton Audio MA1240a Multi-Zone 12 Channel Amplifier