I had a D6 for just under a year, I purchased it in London and then used it in Thailand. I also dive with Uwatec Smart Tec (with AI). In the past year I have over 700 dives with both computers.
Last year I was diving at 7m (DSD) when I started to get a beeping from the D6, it was the depth alarm beeping at 60m, by the time I finished the dive the D6 said that I was at 150m and the water was 127 Celcius, after leaving the water the D6 carried on in Dive mode indefinitely. It was taken back to the distrbutor in Thailand, they contacted me to ask the age, where I purchased it and did I have proof - the answers were 1 year, London and no. They replaced the entire insides of the D6 for 600baht ( 20US$, less than the price of a new battery)
The Uwatec has been perfect, the transmitter is paired for life, none of that silly pairing every time you dive like Suuntos - it just always works, and has been far more reliable than the spg that I also carry (numerous o ring faults, and a cracked glass) - however when it needs a new battery it has to be sent to Hong Kong and takes 2-3 months!!!
Paul