I'd still go after Bourn and figure out who will play LF. If you can have Bourn and Werth at the top of your lineup, that's nearly 10 pitches to start the game every single time and that's before you get to Zim and Haper and LaRoche or whomever they chose to go with.
I don't know. Sure, Bourn gets steals, but Werth is a better leadoff hitter, plain and simple. Sees more pitches, has more patience, gets on base more, has a better contact tool.