Shimmy is even said to provide smoother shifting than campa! Here, in Germany, there are quite a lot of guys who drive this kind of mix.
A bit off-topic: I myself use 10s DA chain with 9s ultegra cassette and 9s chorus/record group. This has solved all the irritating-noise-issues that I had with my 9s chain (due to the difference of 0,2mm in the campa vs. shimmy sprocket spacing, chain occasionally touched the neighboured sprocket)