Actually I had two problems with the LS26, first unit arrives dead with no sound. After speaking with them on the phone they next day aired one with a call tag for the one I had. Then I had a number of issues with the "mute" circuit not un-muting without power off/on cycling. The dealer tried replacing the mute relay 2-3 times and I finally told him that I wanted it sent back to ARC. They received it and determined that the board was bad and just sent out a new unit which was actually a review unit as they were just starting to build the LS27. I kept it for years as I realized that the later production unit had benefited from some updates, my other unit was 35 months old and almost out of warranty.
On the REF5, I had a power circuit board issue and they just replaced the board. All of my experience in dealing with ARC has been handled with the attitude that a music lover cannot be with out his music and they don't want to be the obstacle preventing that from happening.
I have to add that I have really had pretty good experiences with most audio manufacturers with the exception on one or two. It seems like maybe we pay more than we should for good gear but the price includes good service and that needs to be factored in when considering the cost.