The firm I work for has recently had its first joint instruction purporting to arise from the Woolf reforms.
The point I would like to bring is that when appointing joint experts it is vital to maintain communication. In this case, at the same time as appointing us the case was being settled. Our work was put on hold when we questioned this. The problem is that it took several phone calls to get that far, and we have still not been officially told that the case has settled.
This situation will happen more as it takes longer to appoint joint experts, due to the discussions needed and the pressure to settle. As an expert I would ask lawyers to remember the costs ticking on if there are delays in telling experts of changes, and to leave enough time after agreeing on a joint expert for them to do their work.