Although the Sony may be asthetically pleasing to your eye, the Pioneer is built with quality and will out perform that Sony deck. Every single one of the Sony decks I have used have either a) ended up skipping like hell or b) needed to be returned because something mechanical inside had failed. Although I loved my CDX-M670, it skipped over every bump(yes it was installed properly, it did this in various other vehicles also)
Your best bet would be to go with the Pioneer.
- Steve
EDIT - Sony Mobile ES rules!