My recent model LG LED TV does pass full 5.1 down the optical cable, so perhaps Andy's LG should be okay in that regard.

My new Yamaha AV Receiver arrived earlier this week, and sure enough there was a pending update (from this past spring) awaiting it. The release notes said they were fixing something to do with ARC.

As for CEC, I've never used it to date, but have now ordered a CEC splitter so that I can code my MythTV box to automatically power the receiver on/off, and also [EDIT] so the MythTV box/remote can signal volume up/down to the receiver. [/EDIT] I'll let y'all know how that works out once I receive and configure it.