According to Mike Marko, the Arcam rep for American Audio and Video (the American distributor for Arcam), the return rate for the AVR 400 is 1.5%. I checked with 3 different retailers who sold NAD and Arcam, and all thought the Arcam AVR 400 was more reliable than the NAD 775HD2.
The thing that gives me pause is that the AVR 400 is made in China, just like the AVR 2xx and the 300/350. Moreover Arcam pulled production of the AVR 600 from China to England in September of 2010 due to quality control issues. Since the AVR 600 has been made in England it has been more reliable.
Fundamental to the reliability issue is that any AV receiver is likely to be inherently more prone to problems than a 2 channel system as there are more electronic circuits and more "firmware" (i.e. software programs for signal processing) that can become problemmatic.
So why buy Arcam? If you like the Arcam "sound", a fairly neutral sonic field that allows the music to come through as it has been recorded and that doesn't sound overly bright or boomy with bass, it is tough to find anything similar at that price point. Even a used Mcintosh system would run close to $6000 (assuming you picked up a used MX 120 for $2900 and a MC 205 for $3000). For $1500 with the discount program the AVR 400 is a good value. If my budget was closer to $20,000 then I would buy new Mcintosh. Unfortunately I am not going to be buying new Mcintosh.
I was fairly peeved at how Arcam handled my receiver problems a year ago, but after a year of listening to other highly rated receivers at this price point, and 10 months of living with the Anthem, I am going back to Arcam and hope they have gotten the bugs worked out. Their partial buyback program is a step in the right direction.