I'm running the CCDB on my tracer, it adds a fair bit of weight (400g on a 14kg bike!!) but isn't that noticeable when going uphill. Downhill, it is 100 times better than any air shock I have ever owned. The plushness and the way it tracks the ground swallowing any bumps in the trail is totally unmatched by anything else.
Setting up the CCDB is a real minefield. They come setup pretty well out of the factory but 1/2 a turn the wrong way on one of the adjusters can turn the bike characteristics dramatically.
When looking at changing rear shocks, there seems to have been so little choice over the years with little or no innovations that people have just stuck with the stock shocks. The CCDB is so innovative compared to anything else on the market that people seem stunned by its price tag and unwilling to upgrade it even though they would pay £800 for a new set of forks or wheels.
I agree with Si, it does seem that people underestimate the value of a decent rear shock, it makes as much difference to the performance of the bike as a new set of wheels or forks. In fact I would go as far as to say it makes more of a difference than forks as it is constantly under pressure or moving under pedalling forces