The Walther PPx can use a sw mp steel guide rod as an upgrade.I enjoyed his review of this gun, as well. Wound up buying the Walther PPX instead of the SD9VE.
The big thing for me was the Walther's trigger. Light pull, good reset. Although my wife was not happy with my purchase of a semi-auto that lacked an external safety, she loves shooting it. And she's pretty damn good with it.