To import mxf files to FCP X, Aunsoft iMedia converter for Mac will help. It can import in MXF/P2 MXF files from your camcorder directly or from the hard drive and convert MXF to Apple ProRes 422/HQ for FCP. I have tried with the software and the out put files are of high video/audio synchronization.
Aunsoft TransMXF for Mac is another choice to do this work.