Can't say that I'm surprised. I used to work for the X-ray modality (I literally wrote the book on several of their key units) at the Waukesha campus. They had been developing "China-only" products and functions for several years when I left in 2008.
It will be interesting to see if they truly keep all the jobs in Waukesha. While they outsourced quite a few functions (mostly programming to India), the main development, prototyping, and testing took place locally.
GE has done similar headquarters moves before without a large impact to the local offices. In 2005 the global HQ for Healthcare (then called GE Medical Systems) was moved from Waukesha (well, Pewaukee, technically) to London, and the impact was relatively mild.