Reliability so far since launch has been excellent and we've had one on the go without fault - coincidentally alongside a C326 that has been on almost constantly for 12 months without complaint. NAD build to exceptional standards with the back up that if there are issues within the warranty these are usually fixed very quickly.
Only had my 316 for a few weeks so it's way too soon to know about reliability. No problems so far. Looks and sounds great. Love the small case. It's a great amp for the money IMO. I really don't think you need to worry about it any more than any other similarly priced amp.